Article

Ceramic technologies for automotive industry: Current status and perspectives

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Abstract

The automotive industry has developed substantially through advances in mechanical technologies, and technologies such as electronics and advanced materials have also contributed to further advances in automobiles. The contribution of ceramic materials to automobile technologies ranges over driving performance, exhaust gas purification, and fuel efficiency improvements. Several ceramic components, such as knock sensors, oxygen sensors, exhaust gas catalysts, and silicon nitride parts for automotive engines, have been successfully applied to automobiles. This paper focuses on the contribution of ceramics to automotive technologies. It also mentions potential contributions in the future, including adiabatic turbo-compound diesels, ceramic gas turbines, fuel cells, and electric vehicles because ceramic technologies have been intensively involved in the challenge to achieve advanced power sources.

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... Side valve systems used in the early automotive industry have been converted to more efficient systems and in newer vehicles, Double Overhead Cam (DOHC) with four valves per cylinder have been used. This change was made because the overhead cam allows the valves to open and close smoothly, and the multi-valve system is more efficient for exchanging gases in the combustion chambers due to the large openings (Okada, 2009). ...
... Lightweight materials such as silicon nitride (Si 3 N 4 ) and titanium and aluminum alloys have been considered as possible replacements for nickel-based superalloys currently used for exhaust valves. Recently, titanium and aluminum alloys have actually been used in commercial vehicles, while valves made of silicon nitride have been used in very limited quantities in racing formulas (Okada, 2009;Yamagata, 2005). ...
... Fig. 11 shows a ceramic turbocharger made from silicon nitride (Si 3 N 4 ). Turbo lag was reduced in this case due to the fact that silicon nitride is lighter than traditional nickel-based superalloys (Okada, 2009). ...
Chapter
The development of the modern automotive industry requires a reduction in exhaust emissions, fuel consumption and vehicle’s weight, but at the same time an increase in safety and vehicle’s performance. The fulfillment of these complex and mutually contradictory conditions is possible with the application of new modern materials with improved properties as a replacement of traditional materials. The trend of development and application of new composite-based materials has existed for a long time, and continues in the next decade. The application of ceramic-based composite materials (CMC) is increasingly prevalent in the automotive industry, especially in those parts requiring high mechanical durability and high resistance to extreme temperatures with reduced mass. The various types of the ceramic base composites: oxide, silicon carbide (SiC), carbon and other materials are most commonly used as the matrix. Nowadays, CMCs are used to manufacture individual car engine components, valves, turbine parts, exhaust and intake systems, brake disks and brake system parts.
... Due to their high hardness, high young modulus, low density, and low thermal conductivity, these ceramics are applicable to many applications. [25], (b) ceramic turbine rotor [26], (c) ceramic crown [27], (d) unicondylar knee prostheses [28], (e) ceramic femoral head [29], (f) ceramic liner [30], (g) ceramic textile roller, (h) SEM image of SiC abrasive particles [31], (i) catalyst honeycombs used in automobile applications [32], (j) cross-section of a honeycomb [33], (k) Si3N4-based cutting tools [34], (l) Si3N4 ball bearings [35]. Reused with permission from Elsevier. ...
... However, before they are employed in such applications, the products or components made using the ceramics must be manufactured with both high quality and efficiency with attributes such as high-quality surface finish, clean surfaces, dimensional conformity, and high accuracy of shape, in order to prevent and minimize thermal contact, Figure 1. Real/possible applications of ceramics: (a) ceramic implant system in medical application [25], (b) ceramic turbine rotor [26], (c) ceramic crown [27], (d) unicondylar knee prostheses [28], (e) ceramic femoral head [29], (f) ceramic liner [30], (g) ceramic textile roller, (h) SEM image of SiC abrasive particles [31], (i) catalyst honeycombs used in automobile applications [32], (j) cross-section of a honeycomb [33], (k) Si 3 N 4 -based cutting tools [34], (l) Si 3 N 4 ball bearings [35]. Reused with permission from Elsevier. ...
Article
Full-text available
Ceramics are advanced engineering materials in which have been broadly used in numerous industries due to their superior mechanical and physical properties. For application, the industries require that the ceramic products have high-quality surface finishes, high dimensional accuracy, and clean surfaces to prevent and minimize thermal contact, adhesion, friction, and wear. Ceramics have been classified as difficult-to-machine materials owing to their high hardness, and brittleness. Thus, it is extremely difficult to process them with conventional finishing processes. In this review, trends in the development of non-conventional finishing processes for the surface finishing of difficult-to-machine ceramics are discussed and compared to better comprehend the key finishing capabilities and limitations of each process on improvements in terms of surface roughness. In addition, the future direction of non-conventional finishing processes is introduced. This review will be helpful to many researchers and academicians for carrying out additional research related to the surface finishing techniques of ceramics for applications in various fields.
... Recent work lead to improvements in vehicle performance by using different Si 3 N 4 parts, such as reduced-weight valve systems, turbochargers, springs for gas turbines and glow-plugs. 18,19 The design of commercially available, all-ceramic, silicon nitride-based GPs used in this work was detailed in Oprea et al., 1 wherein we have assessed their degradation when heated by dc electric field in ambient air. This paper takes the GP assessment one step further, as the plugs are heated by electricity and are simultaneously exposed to gas combustion environment. ...
Article
In the development of advanced natural gas and hydrogen direct injection combustion engines, a challenge is providing reliable hot-surface (glow plug, GP) ignition systems; most promising are GPs with silicon nitride-based heaters. This paper presents experimental results of accelerated degradation tests of the GPs on natural gas-burning rig, continuing previously published results on GP degradation in air. Degradation, ultimately leading to GP failure, occurs through the synergistic effects of electric field and chemical reactions in the combustion environment. The resulting microstructural modifications of the ceramic heater, studied by SEM/EDS, are a combination of sintering additive ions migration and surface oxidation.
... Compared to the most common structural materials, i.e. steel, the ceramics have lower density and significantly higher resistance to various corrosive factors, including high temperature and abrasion. The ceramics can be used in cutting tools, crucibles for melting metals and glass, tools for semiconductor production, catalyst carriers for removing pollutants from car exhausts, components of car engines, turbochargers, brake discs, etc. [1,2]. The ceramics can also be used in biomedical applications (prostheses) [3][4][5] and as a transparent material for making laser bars, windows or lenses [6]. ...
Article
Fracture toughness, bending strength, Young's modulus, hardness and subcritical crack growth were determined for six different alumina/zirconia composites. The bending strength was modelled using Weibull distribution. The fracture toughness, bending strength and resistance to subcritical crack growth increase as a function of ZrO2 content (stabilized with 3 mol% Y2O3). The authors claim that a threshold stress in a three-parameter Weibull distribution may correspond to a threshold stress intensity factor in which the subcritical crack growth is negligible.
... [23] ...
Conference Paper
Full-text available
Research on the use of thermal barrier coatings in internal combustion engine had contributed in achieving higher thermal efficiency, improved combustion and reduced emissions of the engine. Low thermal conductivity ceramics can be used to control the temperature distribution and heat flow in high temperature structural components due to its inherent thermal insulation properties. For this reason much has been and is being done on the study and development of ceramics for use in automotive engine components working under severe temperature conditions and heavy loads due to their inherent thermal and mechanical properties. The objective of the study is to review the contributions of structural ceramics in the development and improvement of some of the major automotive engine components working under severe conditions of temperature. It is expected that the study will serve as a useful guide for the selection of materials which can withstand severe conditions of temperature and heavy loads for a novel turbocharger and turbocharged engine applications.
... Hitherto, only a few ceramic materials had been found to basically satisfy the basic requirements of thermal barrier coating, and among these materials Yttria Stablized Zirconia (YSZ) is the most generally used and studied material for thermal barrier coating application due to its excellent performance capabilities in applications operating under severe temperature condition like gas turbine and diesel engines [16][17][18][19]. Many applications including but not restricted to automotive industry, gas turbine, nuclear industries, aerospace and heavy-duty utilities such as diesel trucks have benefited from one of thermal barrier coating techniques [20][21][22][23][24][25][26][27][28][29][30]. Functionally graded thermal barrier coating (FG-TBC) is a new thermal barrier coating technique consisting of non-homogeneous materials whose composition and microstructure are varied according to a predetermined profile in order to enhance its thermo-mechanical properties and reduced spallation problems occurring in thermal barrier coated engineering materials [31][32][33]. ...
Conference Paper
Full-text available
Tremendous amount of heat is being lost at the turbine area of an automotive turbocharger during its operation. Application of ceramic thermal barrier coating to components operating under severe temperature condition such as automotive turbocharger turbine volute casing can reduce the heat lost to the environment, improve the efficiency and reliability of components and extend their service life. But high cost of installation and maintenance, complexity and spallation problem due to thermal expansion mismatch between the ceramic and the metal substrate have seriously restricted the acceptance and widespread practice of ceramic thermal barrier coating. In the present study, a solvent based slurry functionally graded thermal barrier coating technique was employed in depositing different compositions of Yttria stabilized zirconia and nickel powders on a nickel alloy substrate using a simple laboratory-scale surface coating machine. The coating compositions of 25wt% YSZ & 75wt% Ni, 60wt% YSZ & 40wt% Ni and 75wt% YSZ & 25wt% Ni were used for the deposition of the first layer, second layer and third layer of the functionally graded coating on the nickel substrate respectively. Experimental validation of heat transfer across the coating and adhesion tests were used to evaluate the suitability and integrity of the functionally graded coating produced for the intended application. The coating microstructure was also analyzed using optical microscope, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). The results have shown that, the functionally graded coating produced has the heat resistance capability of 350C, 1400C and 2500C for one layer, two layer and three layer respectively. The adhesion strength of the coating improved with an increase in the number of the coating layers. There was no spallation problem observed from the coating, also no crack or deformation was observed from the results of the microstructural analysis of the functionally graded coating after the experimental heat transfer tests.
... The application of thermal barrier coating can significantly improve the operating temperature capability, improve the efficiency, reliability and durability of a number of engineering components operating under elevated temperature environments [11] . Many applications including but not restricted to automotive industry, gas turbine, nuclear industries, aerospace and heavy-duty utilities such as diesel trucks have benefited from one of these techniques [9,[11][12][13][14][15][16][17][18][19][20]. Hitherto, only a few ceramic materials had been found to basically satisfy the basic requirements of thermal barrier coating, and among these materials Yttria Stabilized Zirconia (YSZ) is the most generally used and studied material for thermal barrier coating application due to its excellent performance capabilities in applications operating under severe temperature condition like gas turbine and diesel engines [10,[21][22][23][24] . ...
Article
In the present study, the method of slurry coating process was used to fabricate functionally graded thermal barrier coating (FG-TBC) for turbocharger application. An automatic film applicator was used for the coating in an attempt to minimize the production cost of ceramic thermal barrier coatings. Yttria stabilized zirconia ceramic and nickel metal powders were mixed in appropriate proportion and produced a functionally graded material mixture. A slurry based coating method was used for the fabrication of the FG-TBC. The coating compositions of 30wt% Yttria Stabilized Zirconia and 70wt% Nickel, 55wt% Yttria Stabilized Zirconia and 45wt% Nickel as well as 75wt% Yttria Stabilized Zirconia and 25wt% Nickel were used in depositing the first, second and third layers of the functionally graded thermal barrier coating on the substrate respectively. Field Emission Scanning Electron Microscopy, Scanning Electron Microscope and X-ray Diffraction were used to study and evaluate the integrity and reliability of the coating produced. The results have indicated the sustainability and suitability of the method adopted in the study with regards to the production of good and quality functionally graded thermal barrier coating with no spallation problem and having good adherence to the substrate.
... Nickel alloy with commercial purity of 99.7 % was used in this study as the substrate material for the coatings based on the cost implication and ease of availability in comparison to tungsten, which is currently the material used in turbine volute for automotive engines. Nickel alloy has relatively inherent thermal and mechanical properties capable of withstanding the working environment for the turbocharger application [15][16][17]. Furthermore, a glow discharger spectrometer (GDS) test was carried out on the Nickel alloy material in order to confirm its elemental composition. ...
Conference Paper
Full-text available
Engine downsizing has been proven to improve fuel economy and turbocharging is considered to be one of the key enablers. Turbine volute which experiences extreme temperature needs to be made from durable and cost effective material. Alternatively, thermal barrier coating could be used to insulate a cheaper and lighter material, so it could operate in extreme temperature conditions. This paper describes an attempt to improve the thermal properties of nickel metal (substrate) through the use of simple and cost effective functionally graded thermal barrier coating technique, as an alternative choice for turbocharger turbine volute casing material. Commercial computational tools were used to predict the heat transfer behaviour as well as engine level effects of different functionally graded thermal barrier coating layers. The coating slurry was developed using appropriate mixture of yttria-stabilized zirconia (YSZ) and nickel (Ni) powder, distilled water, polyvinyl alcohol and ammonium citrate tribasic. The three different compositional layers of the coating were deposited on the nickel substrate using an " automatic film applicator ". The design compositions of Sample A (30wt% YSZ & 70wt% Ni), Sample B (55wt% YSZ & 45wt% Ni) and Sample C (75wt% YSZ & 25wt% Ni) produced the best coating result for the first, second and third layer respectively. The optimum percentage for the best slurry composition were found to be 45.5wt% ceramic-metal, 51.20wt% solvent, 3wt% binder and 0.3wt% dispersant. With an initial temperature of 750°C, the heat resistance capability was found to be 40°C, 130°C and 250°C for the first, second and third layer respectively. The average turbine efficiency of 54.1%, 59.2%, 63.4% and 68.03% were achieved for the engine speed of 1000rpm, 1500rpm, 2000rpm and 2500rpm, respectively. Similarly, the compressor efficiency was found to be 59.3%, 62.2%, 65.5% and 69.97 respectively. Introduction Automotive turbocharger turbine is being subjected to high temperature and corrosive exhaust gases. The extreme temperature leads to heat transfer issues which affect the engine-turbo matching as well. Furthermore, the high temperature conditions necessitate the turbine casing material to be highly durable. The structure of a turbocharger is complicated and its working environment is severe, thus it is one of the high risk components in an engine [1]. The lifespan of a turbocharger, its efficiency and reliability can be affected by factors such as the modality of the turbine-engine conduction [2]. In addition, the high cost and high density of tungsten, which is the material currently used for this purpose has made the turbocharger relatively expensive and heavy. As a result, researchers and engineers are hitherto intensifying effort towards improving the turbocharger reliability and service life for better performance at lower manufacturing cost [3]. Furthermore, the thermal energy transfer from the turbine has serious effect on the turbocharger overall performance as it restrict the engine charging process which significantly reduces the turbine power and influences turbo lag at no-load and part-load engine operations as well as during engine start up [4]. Also the unrelenting quest of fuel economy improvement in automotive and gas turbine engines has aggravated the situation and thus compelled researchers, engineers and designers to find alternative way(s) of improving the thermal efficiency of engines and high temperature capability of the existing engine components through the use of thermal barrier coating techniques. Functionally graded thermal barrier coating (FG-TBC) is a new technique consisting of non-homogeneous materials whose composition and microstructure are varied according to a predetermined profile. This is done in order to enhance its thermo-mechanical properties and reduced spallation problems occurring in thermal barrier coated engineering materials [5-7]. Two or more different materials (in powder form), in most cases ceramic and metal, are mixed and used depending on the objective, applications and the nature of the substrate material. Recent studies have shown that FG-TBC technique had received a lot of attention from various applications in the field of science and engineering. Some of the applications are for heat-resistance, electronic, biological and chemical engineering [5]. The aim of the present study is to evaluate the quality, integrity and reliability of slurry based functionally graded thermal barrier coating (FG-TBC) deposited using automatic film applicator with respect to thermal efficiency improvement in automotive turbocharged engines.
... The application of thermal barrier coating can significantly improve the operating temperature capability, improve the efficiency, reliability and durability of a number of engineering components operating under elevated temperature environments [11]. Many applications including but not restricted to automotive industry, gas turbine, nuclear industries, aerospace and heavy-duty utilities such as diesel trucks have benefited from one of these techniques [9,[11][12][13][14][15][16][17][18][19][20]. ...
... Among wear resistant materials silicon nitride ceramics and their composites represent an outstanding role as materials widely used for different frictional application like heavy duty automotive components (in gas turbine, ceramic bearings, turbocharger rotors, exhaust control valves, rocker arm tips, swirl chambers) [4][5][6][7] or tool materials for common technologies (centring pins, drawingand tube forming tools, welding rollers, gas nozzles) [8][9][10], or high performance tool materials for advanced green technologies like dry metal forming or dry cutting [11,12]. ...
Article
Hot isostatically pressed monolithic and multilayer graphene (MLG) reinforced silicon nitride nanocomposites have been investigated by ball-on-disc tests under variable loading conditions. Tests were carried out at room temperature with three different normal loads (10, 40 and 80 N), and six sliding speeds (10, 20, 50, 100, 150 and 200 mm/s) without lubrication using commercial silicon carbide ball counterparts for 54 tribosystems. The aim of the research work was to construct 2D wear transition and 3D wear rate maps of the investigated ceramic composites. The 3D maps visualizing the specific wear rate and the dimensionless wear coefficient as a function of normal load and sliding speed have been completed with morphological analysis of wear tracks and identification of the dominant wear mechanisms. The presented ceramic wear maps provide useful aid for predicting the wear performance of the investigated nanocomposites under various loading conditions.
... The ionic conductivity is a key property for applications including solid oxide fuel cells and solid oxide electrolyzer cells for energy storage, 1,2 oxygen sensors similar to the lambda sensor in cars, which controls the combustion of fuel, 3 as well as oxygen membranes. 4−7 For a better understanding, oxygen ion conductivities have been calculated in the commonly used material rare-earth doped ceria using analytical models, 8−12 Molecular Dynamics (MD) simulations, 13−18 and Kinetic Monte Carlo (KMC) simulations. ...
... Additionally, they reveal chemical stability in oxidizing and reducing atmospheres [13,14]. Common utilized electrolyte materials are partially stabilized 3YSZ and fully stabilized 8YSZ [15,16]. Thermal barrier coatings (TBCs) are the solution for long-term and short-term problems in high-temperature electrochemical devices, such as gas turbines, gas separators, gas reformers and power generation industry [17][18][19][20]. ...
Article
The growth of inventive high-temperature electrochemical devices such as solid oxide fuel cells constitutes a major task in brazing technology of ceramic–metal joints. In this work, reactive air brazing was used and the joining characteristics of 3YSZ with Crofer 22 APU have been systematically analyzed for three different brazing temperatures (1000, 1050 and 1100 °C) and two dwell times (5 and 30 min). The joints have been brazed successfully using the Ag–4CuO filler alloy. This braze filler metal was manufactured by an arc PVD (physical vapor deposition) process. Further, sufficient wetting of the zirconium oxide was achieved. The morphology of the oxide reaction layer at the steel side had a major influence on the shear strength of the brazed joints. A maximum average shear strength of 101 ± 4 MPa was obtained for a temperature of 1050 °C and a dwell time of 5 min.
... For example, in tire manufacturing carbon black particles are bonded with a rubber matrix to form an abrasion resistance material with enhanced tensile strength [1]. Brake disks made of a carbon-ceramic composite are 65% lighter than the traditional cast iron ones and maintain a high friction coefficient even at elevated temperatures [2]. In electronic packaging, the enhancement of polymers with metal particles leads to a composite with polymer mechanical properties and boosted thermal or electrical conductivities [3]. ...
Preprint
Accurate thermal analysis of composites and porous media requires detailed characterization of local thermal properties in small scale. For some important applications such as lithium-ion batteries, changes in the properties during the operation makes the analysis even more challenging, necessitating a rapid characterization. We propose a new method to characterize the thermal properties of particulate composites based on actual micro-images. Our computer-vision-based approach constructs 3D images from stacks of 2D SEM images and then extracts several representative elemental volumes (REVs) from the reconstructed images at random places, which leads to having a range of geometrical features for different REVs. A deep learning algorithm is designed based on convolutional neural nets to take the shape of the geometry and result in the effective conductivity of the REV. The training of the network is performed in two methods: First, based on implementing a coarser grid that uses the average values of conductivities from the fine grid and the resulted effective conductivity from the DNS solution of the fine grid. The other method uses conductivity values on cross sections from each REV in different directions. The results of training based on averaging show that using a coarser grid in the network does not have a meaningful effect on the network error; however, it decreases the training time up to three orders of magnitude. We showed that one general network can make accurate predictions using different types of electrode images, representing the difference in the geometry and constituents. Moreover, training based on averaging is more accurate than training based on cross sections. The study of the robustness of implementing a machine learning technique in predicting the thermal percolation shows the prediction error is almost half of the error from predictions based on the volume fraction.
... Si 3 N 4 is one of the most famous non-oxide ceramics for structural/functional applications due to its exceptional properties such as excellent thermal/chemical resistance, high mechanical strength and hardness, low thermal expansion coefficient, high melting point, and low density [1][2][3][4][5]. Therefore, it has been used in a wide range of applications such as hightemperature structural materials (heat engines, bearings, turbine blades, cutting tools, etc.) [6,7], aerospace [8] and automotive industries [9], medical and orthopedic applications [10,11], and electrical/thermal insulators [12]. ...
Article
Full-text available
The monomer content in the gelcasting process affects the kinetics of cross-linking reactions which determines the quality of the gel network structure and the final properties of the material. The main purpose of this study was to optimize the monomer contents in the gelcasting process to achieve a dense Si3N4 body by using pressureless sintering. Si3N4 bodies with a relative density of 95.9 ± 0.5% and 605 ± 4 MPa flexural strength were successfully prepared by employing the gelcasting technique using high-solid load slurry of 76 wt%. Acrylamide (AM) and N, N′-methylenebisarylamide (MBAM) were adopted as the monomeric system. The quality of gel structures was characterized by measuring idle time, green flexural strength, and linear shrinkage. Phase composition and microstructure of sintered samples were identified using XRD and SEM analysis, respectively. The linear drying shrinkage and Idle time decreased by increasing the monomer content. However, flexural green strength did not monotonically change with monomer content. The slurry with a 6 wt% monomer and AM/MBAM ratio of 3 produced the optimized gel structure. Besides, it resulted in a higher amount of β-Si3N4 phase which gives better mechanical strength.
... This has implications for the use of ceramic materials in aviation, automobiles, medicine, and the chemical industries. Although sensors in many areas are made of ceramics, the fragility of these materials limits their application in construction materials (Okada, 2009). ...
Article
Full-text available
We are living in a sensor world. Sensors are used in the house, office, car, and other areas detecting our presence by turning lights on, adjusting room temperature, detecting fires, and many other tasks. Today sensor has become a “buzz word”, without which it is hard to imagine living. They play a vital role in all sectors including housing, industry, aviation, medicine, and automobiles to name a few. Sensors can be manufactured with many types of materials. However, sensors made of ceramics have significance and have advantages when compared to those made from other materials. This mini review examines ceramic sensors and their applications in various sectors including the materials used to build them and their functioning in different areas. The paper precisely reports ceramic sensors and their applications in industry, including the medical, automotive, and aviation sectors.
Article
Ceramic composites (CCs) are mixtures of different phases, and their development is often regarded as a milestone in technological progress. They are used in practically all significant industries. Frequently, CCs are exposed to variable dynamic loads, impacts or high temperatures [1-3]. In this paper, the impact of thin plates fabricated from Al2O3/ZrO2 is analyzed. The plates are made of the above CC with different proportions of its components. Damage progression is analyzed using peridynamics, similarly to quasi-static tension [4]. The purpose of the study is to describe the impact damage development in the CC plates and determine the role of phase contents. It has been found that phase ratios in the tested CC are vital for the behavior of the plates. In conclusion, it can be claimed that the employed peridynamic approach is suitable for solving the problems under study and that the impacting plates should be treated as real three-dimensional structures.
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Ceramic matrix composites (CMCs) can be attractive for structural applications, but their machining by conventional methods is expensive and often critical. Complex geometries on advanced ceramics require contactless processes, such as electro discharge machining (EDM) or -drilling (EDD). These proved to be viable for CMCs with electrical resistivity below a critical value in the range of 1-3 Ωm. The condition is complied with by many CMCs: an example is alumina with titanium carbide. Material removal of ceramics by electrical discharges is a complex process involving different mechanisms, depending on the process setup. The paper describes an experimental study on EDD of 0.4 mm diameter holes with aspect ratio of 20 in Al2O3-TiC, using copper electrodes. Peak current (Ip), pulse-on time (ton) and pulse-off time (toff) are varied as independent variables. Four performance indicators are measured: material removal rate (MRR), electrode wear rate (EWrate), overcut (OC) and surface roughness (Ra, Sa). Empirical models are proposed to describe t the effect of process parameters on the output indicators. The analysis is supported by the observation of the surface and subsurface morphology, with the aim of investigating the material removal mechanisms and attaining a full comprehension of macroscopic results. It is found that removal mostly occurs by melting and evaporation and that surface morphology is determined by two phenomena ruled by pulse power. A process description is proposed, built around power as the ruling factor.
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A novel catalyst of over Ti3AlC2 ceramic was prepared by an impregnation method. The resulting catalyst exhibited high catalytic activity and selectivity for the esterification of benzoic acid to ethyl benzoate. This study realized 80.4% conversion for benzoic acid and >99% selectivity for ethyl benzoate under 120 °C at 34 h. Various characteristics of the reaction were studied, such as performance of Ti3AlC2 and /Ti3AlC2, the influence of bases, reaction temperature, reaction time, and recycling of the catalyst. In order to further study this reaction system, the XRD and FT-IR of /Ti3AlC2 was detected and analyzed. All results indicate that /Ti3AlC2 can serve as an acid catalyst.
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Based on the author's lectures to graduate students of geosciences, physics, chemistry and materials science, this didactic handbook covers basic aspects of ceramics such as composition and structure as well as such advanced topics as achieving specific functionalities by choosing the right materials. The focus lies on the thermal transformation processes of natural raw materials to arrive at traditional structural ceramics and on the general physical principles of advanced functional ceramics. The book thus provides practice-oriented information to readers in research, development and engineering on how to understand, make and improve ceramics and derived products, while also serving as a rapid reference for the practitioner. The choice of topics and style of presentation make it equally useful for chemists, materials scientists, engineers and mineralogists.
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Material innovations in automotive technologies are presented in this chapter. The automotive industry has developed substantially through advances in mechanical technologies, and technologies such as electronics and advanced materials have also contributed to further advances in automobiles. The contribution of materials to automobile technologies ranges over driving performance, exhaust gas purification, and improved fuel efficiency. Advanced materials such as high strength steels, aluminum alloys, polymeric materials and composites contributed to the weight reduction in automobiles. Wear-resistant materials enhanced the durability of gears and bearings, and the low friction materials such as diamond-like carbon coating, in particular applied to valve systems, enhanced the fuel economy resulting from the reduction in friction loss. Advances in magnetic materials led to the realization of compact and powerful motors. Several ceramic components, such as knock sensors, oxygen sensors, exhaust gas catalysts, and silicon nitride parts for automotive engines, have been successfully applied. A variety of rechargeable batteries have been developed since the invention of lead-acid batteries, and nickel metal hydride batteries and lithium ion batteries have been used in the advanced automobiles. A variety of electronic devices were introduced into automobiles in a course of advancing car electronics, and the properties of the functional materials used in the devices are presented with the device structures. It also mentions potential contributions to power sources in the future, including adiabatic turbocompound diesels, ceramic gas turbines, fuel cells, and electric vehicles because material technologies have been intensively involved in the challenge to achieve the advanced power sources.
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This paper aims to investigate the internal structure and to evaluate the elastic and strength characteristics of the corundum ceramic samples sintered at different temperatures. The average value of porosity of the sintered samples at the temperatures of 1400, 1500, and 1600 °C is 33, 26, and 17%, respectively. Mechanical tests of the ceramic samples are performed using the threepoint bending method. The ultimate bending strength varies from 135 to 265 MPa in the studied sintering temperature range. The elastic moduli of the sintered samples are found to be in the range of 58 – 113 GPa. An analysis of the ceramic samples’ microstructure is performed using a scanning electron microscope. The dependence of the porosity, pore size, and grain size on the sintering temperature is indicated. The values of strength and elastic modulus of the samples increase nonlinearly with rising sintering temperature in the experiment. Statistical behavior of mechanical properties of the ceramic samples is described using the Weibull analysis. The strength data for the sintering temperatures of 1500 and 1600 °C are well described by the Weibull distribution, and the strength values for a sintering temperature of 1400 °C are described with a significant scatter.
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Ceramic composites are used in such industries as the armaments industry, aviation, automotive, nuclear power, and space exploration. In several areas, they stand for the source of technological progress. The material is often subjected to extreme loads, such as variable dynamic loads and high temperatures. Peridynamics is a non-local, meshless quite recently formulated method of stress analysis. The methods appear to be useful in the analysis of brittle materials. In the paper, an impact model of an Al2O3/ZrO2 a thin plate is investigated. A brittle damage model is used for both phases of the composite. The attention is focused on damage initiation and distribution in the impacting sample.
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We develop the method of production of conductive vacuum-tight ceramics based on Al2O3 modified by multiwall carbon nanotubes (MWCNTs) at extremely low their content. The method is based on the use of nanopowders of α-Al2O3 combined with application of highly efficient distribution of MWCNTs on the surface of the initial oxide particles, provided by using ultrasonicated MWCNT suspensions stabilized with surfactant. The usage of surfactant destructing of MWCNT agglomerates of structure results in the elimination of cavities in ceramic matrix and improvement vacuum-tight properties of composites. The results can provide the optimization of production technology of strong vacuum-tight ceramics which are perspective for the production of conducting ceramics for accelerating tubes in pulse linear accelerators. Such materials would make it possible to avoid using high-voltage resistive voltage splitters and simultaneously suppress transverse resonance modes usually leading to transverse instability of intense beams in long accelerating structures.
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When manufacturing transparent multilayer armor of high threat level, the reinforced silicate glass and transparent ceramics with protecting back films are usually used. The hardness of the front layer of the shield should be much higher than that of the impactor. A promising option isthe use of a single leucosapphire crystal. However, due to its high cost and the impossibility of providing large-sized samples, the transparent polycrystalline materials are developed. One of the most advanced materials is ALON, which is close to leucosapphire in strength characteristics. The aim of this work is to develop a mathematical model to calculate the impact interaction of fragmentation elements with transparent armor. The numerical study is carried out using proprietary software systems. Calculations of the high-speed impact of the steel cylindrical impactor are implemented for three types of shields made of transparent armor. The first two-layer target is made of 20 mm thick tempered glass and a 4 mm thick polycarbonate layer. The second and third targets are three-layered. The front layer of the second target is made of ALON, and the spinel is used for the third one. The second and third layers in these targets are made of tempered glass and polycarbonate, respectively. The calculated results show that ALON is the most impact-resistant material, while spinel is a little less resistant.
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Thermal barrier coatings (TBCs) were used to simulate adiabatic engines with the intention not only for reduced in-cylinder heat rejection and thermal fatigue protection of underlying metallic surfaces, but also for possible reduction of engine emissions. In this research work, the main emphasis is placed on investigating the effect of a TBC on the engine fuel consumption with the support of detailed sampling of in-cylinder pressure. Emission measurements of unburned hydrocarbons and carbon monoxide were also conducted in this study. In the present investigation, the piston crown was coated with the YSZ (Y₂O₃&ZrO₂) ceramic material, using a plasma spraying technique. YSZ (Y₂O₃&ZrO₂) was deposited to a thickness of 250 microns over the piston crown. Investigation showed that, Increasing the brake thermal efficiency, NOx emission and O2 and decreasing the specific fuel consumption, CO and HC emissions for Low heat Rejection engine with thermal coated piston compared to the standard engine. The peak cylinder pressures were increased by a magnitude up to 6 bars in the TBC piston engine, in particular at high engine power outputs, though the exhaust gas temperatures were generally lower, indicating good gas expansion in the power stroke which caused the peak cylinder pressure to raise and that impacted on brake thermal efficiency which is increased by 1.4%.
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The traditional method for shaping of ceramics is by slip casting on gypsum moulds; however, its application for near net shaping of ceramic components is limited due to contamination by calcium ions. The focus of this study is the modification of the mould to limit Ca²⁺ contamination and to maintain favourable sucking properties. Cement was added to a standard gypsum mould to suppress its erosion, and a decrease in the sucking rate was observed due to its reduced macroporosity. The highest values of green densities were obtained at gypsum/cement weight ratios of 90/10 and 70/30. The microstructure analysis showed that the alumina blocks prepared from the moulds containing higher quantities of cement (30 or 50 wt%) were resistant to the abnormal grain growth caused by Ca²⁺ contamination from the gypsum. The gypsum/cement mixtures for making moulds for slip casting significantly limit mould erosion due to a lower sucking rate and abnormal grain growth of the slip cast samples because of the decreased diffusivity of Ca²⁺ ions. Therefore, the present modification of the mould renders the slip casting method more suitable for the near net shaping of ceramics. This article is protected by copyright. All rights reserved.
Thesis
The study of nano-objects is of particular interest due to their outstanding mechanicalproperties. While metal nanocrystals are generally characterized by high yield strength and ductility under extreme compressive stress, very few is known about other classes of materials including ceramic or semi-conductors. Recently, it was shown that ceramic nano-particles such as aluminum or magnesium oxides could plastically deform under high stress without cracking what might have significant implications for the sintering and compaction of nanocrystalline ceramics. However, only few evidences of the elementary deformation processes were addressed so far, especially in the case of α-Al2 O3 nanocrystals. In this study, we propose to investigate α-Al2 O3 nanoparticle mechanics using molecular dynamics simulations. Firstly, several α-Al2O3 bulk properties as lattice and elastic constants, stacking-fault and surface energies as well as basal edge dislocation features as compared to existing experimental/numerical literature are investigated to test the transferability of various interatomic force fields to the nanomechanical field. Among all the tested parameterizations, the 2/3-body Vashishta interatomic potential has shown to be particularly adapted to the overall study. Secondly, nanoparticle compression tests are modeled as function of orientation and temperature including a detailed analysis of dislocation-based mechanisms for several sizes of α-Al2O3 nanoparticles. Results are discussed in the context of recent nanomechanics experiments as well as pioneer works performed on bulk alumina.
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The article presents the results of sintering a composite graded ceramic based on Al 2 O 3 / ZrO 2 using a focused electron beam. To prevent surface charging, sintering was carried out in the forevacuum pressure range. It was demonstrated that under electron beam exposure, the surface temperature reaches 1600 degrees within 20 minutes. The distribution of elements over the depth of sintered specimens is presented. The dependence of the temperature difference over the sample as a function of the number of layers in the sample is shown. The value of the temperature drop along the depth of the sintered sample is calculated and recommendations are given for reducing the temperature drop.
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This paper presents a material combination that reduces the friction coefficient markedly to a superlow friction regime (below 0.01) under boundary lubrication. A state approaching superlubricity was obtained by sliding hardened steel pins on a hydrogen-free diamond-like carbon (DLC) film (ta-C) lubricated with a poly-alpha-olefin (PAO) oil containing 1 mass% of an ester additive. This ta-C/steel material combination showed a superlow friction coefficient of 0.006 at a sliding speed of 0.1 m/s. A hydrogencontaining DLC coating/steel combination also showed a lower friction coefficient in air than a steel/steel combination, 0.1 vs. 0.8, but no large reduction was observed when the sliding surfaces were lubricated with ordinary 5W-30 engine oil and the PAO oil containing an ester additive. The friction coefficient of the hydrogen containing DLC/steel combination lubricated with the PAO containing an ester additive was above 0.05. On the other hand, the superlow friction performance demonstrates that the rolling contact friction level of needle roller bearings can be obtained in sliding contact under a boundary lubrication condition. It is planned to apply this advanced DLC coating technology to valve lifters lubricated with a newly formulated engine oil in actual mass-produced gasoline engines. A larger friction reduction of more than 45% is expected to be obtained at an engine speed of 2000 rpm.
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Automotive three-way catalysts (TWCs) have represented over the last 25 years one of the most successful stories in the development of catalysts. The aim of this paper is to illustrate the technology for abatement of exhaust emissions by analysing the current understanding of TWCs, the specific role of the various components, the achievements and the limitations. The challenges in the development of new automotive catalysts, which can meet future highly demanding pollution abatement requirements, are also discussed.
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This paper reviews the status of structural ceramics in Japan. Until around 1980, successful applications of these materials were limited to wear-resistant parts and structural components working under very low stresses. Considerable work has been done over the years on applying ceramics to mechanical parts used under higher stresses. This led to some successful applications of silicon nitride to automotive components, including turbocharger rotors and glow plugs. However, the recent market for silicon nitride automotive components has not been as large as was expected. Cordierite honeycombs for catalysts and diesel particulate filters made of silicon carbide are becoming more important applications in Japan.It is noteworthy that the Japanese market for structural ceramics has been steadily increasing since 1985, with the leading applications being apparatus for purifying the exhaust gas of automotive engines and parts for semiconductor manufacturing equipment. Alumina, for example, is widely used for vacuum process chambers. High-purity alumina is also used for the components of liquid crystal device manufacturing equipment and various mechanical parts. The recent applications of structural ceramics in Japan summarized in this review include vacuum process chambers for manufacturing semiconductor and liquid crystal devices, wear-resistant ceramics used for steel-making, optical lens forming and cutting tools, refractory tubes for casting aluminum alloys, and automotive applications.
Chapter
Aircraft brake manufacturers are meeting the challenge of reducing the weight of the braking system by using carbon/carbon (C/C) composite materials which serve as the friction material, heat sink. and structural components. Different types of C/C composite materials, their processing and properties are discussed.
Chapter
IntroductionDevelopment TargetDevelopment ScheduleEngine Configuration and Design FeaturesAdvanced Utilization of CeramicsEngine Test ResultsResearch and Development on Practical Industrial Co-Generation TechnologySummary
Conference Paper
Ceramic matrix composite (CMC) materials based on 2D-carbon fibre preforms show high heat-absorption capacities and good tribological as well as thermomechanical properties. To take advantage of the full lightweight potential of these new materials in high performance automotive brake discs, the thermal conductivity transverse to the friction surface has to be high in order to reduce the surface temperature. Experimental tests showed, that lower surface temperatures prevent over-heating of the brake's periphery and stabilizes the friction behaviour. In this study different design approaches with improved transverse heat conductivity have been investigated by finite element analysis. C/C-SiC bolts as well as SiC coatings and combinations of them have been investigated and compared with an orthotropic brake disc, showing a reduction of temperature of up to 50%. Original sized brake discs with C/C-SiC have been manufactured and tested under real conditions which verified the calculations. Using only low-cost CMC materials and avoiding any additional processing steps, the potential of C/C-SiC brake discs are very attractive under tribological as well as under economical aspects.
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By the early 1970s increased use of cars in some major cities had resulted in serious concerns about urban air quality caused by engine exhaust gas emissions themselves, and by the more harmful species derived from them via photochemical reactions. The three main exhaust gas pollutants are hydrocarbons (including partially oxidised organic compounds), carbon monoxide and nitrogen oxides. Engine modifications alone were not sufficient to control them, and catalytic systems were introduced to do this. This catalytic chemistry involves activation of small pollutant molecules that is achieved particularly effectively over platinum group metal catalysts. Catalytic emissions control was introduced first in the form of platinum-based oxidation catalysts that lowered hydrocarbon and carbon monoxide emissions. Reduction of nitrogen oxides to nitrogen was initially done over a platinum/rhodium catalyst prior to oxidation, and subsequently simultaneous conversion of all three pollutants over a single three-way catalyst to harmless products became possible when the composition of the exhaust gas could be maintained close to the stoichiometric point. Today modern cars with three-way catalysts can achieve almost complete removal of all three exhaust pollutants over the life of the vehicle. There is now a high level of interest, especially in Europe, in improved fuel-efficient vehicles with reduced carbon dioxide emissions, and “lean-burn” engines, particularly diesels that can provide better fuel economy. Here oxidation of hydrocarbons and carbon monoxide is fairly straightforward, but direct reduction of NOx under lean conditions is practically impossible. Two very different approaches are being developed for lean-NOx control; these are NOx-trapping with periodic reductive regeneration, and selective catalytic reduction (SCR) with ammonia or hydrocarbon. Good progress has been made in developing these technologies and they are gradually being introduced into production. Because of the nature of the diesel engine combustion process they produce more particulate matter (PM) or soot than gasoline engines, and this gives rise to health concerns. The exhaust temperature of heavy-duty diesels is high enough (250–400 °C) for nitric oxide to be converted to nitrogen dioxide over an upstream platinum catalyst, and this smoothly oxidises retained soot in the filter. The exhaust temperature of passenger car diesels is too low for this to take place all the time, so trapped soot is periodically burnt in oxygen above 550 °C. Here a platinum catalyst is used to oxidise higher than normal amounts of hydrocarbon and carbon monoxide upstream of the filter to give sufficient temperature for soot combustion to take place with oxygen. Diesel PM control is discussed in terms of a range of vehicle applications, including very recent results from actual on-road measurements involving a mobile laboratory, and the technical challenges associated with developing ultra-clean diesel-powered cars are discussed.
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It has now been over 25 years since the introduction of the catalytic converter to reduce emissions from the internal combustion engine. It is considered one of the greatest environmental successes of the 20th century, however, new emission control technologies are still being developed to meet ever more stringent mobile source (gasoline and diesel) emissions. This short review will discuss the basis for improvements and highlight technology area, which will require further improvements in emissions and fuel economy. Some of the issues related to fuel cells which some believe may replace the internal combustion engines for automobile applications is also be briefly discussed.