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Publications (90)
Silicon nitride possesses a variety of excellent properties that can be specifically designed and manufactured for different medical applications. On the one hand, silicon nitride is known to have good mechanical properties, such as high strength and fracture toughness. On the other hand, the uniqueness of the osteogenic/antibacterial dualism of si...
In this work, we report an innovative and facile UV light-assisted synthesis of a nanocomposite based on silicon oxycarbide (SiOC) and tin nanoparticles. SiOC ceramic matrix, containing a conductive free carbon phase, participates in lithium-ion storage, and buffers the volume changes of Li-alloying/de-alloying material. The reported synthesis proc...
The aim of this study was to develop a ZrO2-Al2O3 composite coating with excellent mechanical, corrosion, and tribocorrosion behaviour on Zr-2.5 Nb alloy substrate for load-bearing implants. The bipolar waveforms utilizing cathodic duty cycles of 10, 20, and 40 were applied to produce composite coatings using the plasma electrolytic oxidation in an...
In this work, we present the characterization and electrochemical performance of various ternary silicon oxycarbide/graphite/tin (SiOC/C/Sn) nanocomposites as anodes for lithium-ion batteries. In binary SiOC/Sn composites, tin nanoparticles may be produced in situ via carbothermal reduction of SnO2 to metallic Sn, which consumes free carbon from th...
Ceramics are highly technical materials with properties of interest for multiple industries. Precisely because of their high chemical, thermal, and mechanical resistance, ceramics are difficult to mold into complex shapes. A possibility to make convoluted ceramic parts is to use preceramic polymers (PCP) in liquid form. The PCP resin is first solid...
Hollow ceramic spheres are considered as an excellent buoyancy unit for deep-sea applications (> 5,000 m). However, there is no successful commercialization due to the low productivity of conventional slip casting because of the short life span of gypsum molds. In this work, we have developed single-use pulp-based molds for ceramic slip-casting app...
Polymer-derived ceramics exhibit excellent properties and are compatible with many shaping techniques due to their liquid precursors. We present a fast and pressureless process for the fabrication of SiCN. Using varied amounts of the filler divinyl benzene, defect-free monolithic disc samples are obtained at high yields. Their electrical conductivi...
Aluminum alloys are well known light-weight alloys and very interesting materials to optimize the strength/weight ratio in order to reduce automotive vehicle weight, fuel consumption and CO2 emissions; unfortunately, they are also relatively soft and therefore cannot be used for high wear applications.
The aim of this work was to develop an aluminu...
Ceramics are highly technical materials with properties of interest for multiple industries. Precisely because of their high chemical, thermal, and mechanical resistance, ceramics are difficult to mold into complex shapes. A possibility to make convoluted ceramic parts is to use preceramic polymers (PCP) in liquid form. The PCP resin is first solid...
Natural spinal tissues have unique dynamic properties and it is crucial to investigate the full dynamic response of spinal implants and related biomedical materials to ensure compatibility with the host tissue. Silicon nitride is a promising bioceramic for spinal implants. In this study, the mechanical properties and dynamic response of silicon nit...
The mechanical behavior of 3 mol% Y2O3-ZrO2 ceramic and 21 wt.% Al2O3-3 mol% Y2O3-ZrO2 ceramic composite with submicron grain size was studied. Mechanical properties, such as hardness, Young's modulus, four-point bending strength, and fracture toughness of both materials were measured. Linear stress-strain deformation behavior of both 3 mol% Y2O3-Z...
The aim of this work was to study cyclic stress–strain deformation behavior of LaCoO3 as a function of loading and heating history. The ferroelastic hysteretic deformation of LaCoO3 at different stresses and temperatures was characterized using effective Young’s modulus, hysteresis loop area and creep strain shift parameters. The deformation behavi...
Selected studies on synthesis, Spark Plasma Sintering, crystal structure and microstructure analysis along with mechanical properties by nanoindentation are presented for ZrB2, HfB2, OsB2, and IrB2 ceramics. ReB2 type hexagonal OsB2 and IrB2 powders were synthesized by mechanochemistry of their precursor elements, while commercial ZrB2 and HfB2 pow...
In an implantable electrode, such as a pacemaker electrode, fibrotic tissue formation due to a foreign body reaction is an important challenge affecting the efficiency to transmit the electrical signal of the device. The chemical inertness, biocompatibility, and electrical conductivity of polymer-derived ceramics (PDCs) are promising features in te...
Morphology, phase composition, cracks and porosity are investigated in monolithic Ti modified SiOC polymer-derived ceramics pyrolyzed at 1000°C and 1400°C using synchrotron X-ray full field absorption-contrast tomographic microscopy and scanning XRF- and XRD-contrast microscopy. Samples pyrolyzed at 1000°C show a crack-free structure, but pyrolysis...
Silicon oxycarbide (SiOC) has recently regained attention in the field of Li-ion batteries, owing to its effectiveness as a host matrix for nanoscale anode materials alloying with Li. The SiOC matrix, itself providing a high Li-ion storage capacity of 600 mAh g-1, assists in buffering volumetric changes upon lithiation and largely suppresses the fo...
Additive manufacturing (AM) methods are being integrated in ceramics fabrication either as the main manufacturing tool or for auxiliary purposes. By using polymers, powders and preceramic formulated materials, AM techniques are pushing towards higher resolution, lower shrinkage and shorter building time. Herein, we present the fabrication of cerami...
The structural, thermal, electrical and mechanical properties of fully dense B4C ceramics, sintered using Spark Plasma Sintering (SPS), were studied and compared to the properties of B4C ceramics previously published in the literature. New results on B4C’s mechanical responses were obtained by nanoindentation and ring-on-ring biaxial strength testi...
Na-β”-alumina ceramics are applied as electrolytes in high-temperature Na/NiCl2 and Na/S batteries. Although featuring excellent sodium-ion conductivity in the order of 0.2 S cm⁻¹ at 300 °C, the brittleness associated with ceramic materials makes Na-β”-alumina electrolytes vulnerable to mechanical stresses, e.g. during battery operation. In this st...
Polymer-derived ceramics (PDC) have recently gained increased interest in the field of bioceramics. Among PDC's, carbon-rich silicon oxycarbide ceramics (SiOC) possess good combined electrical and mechanical properties. Their durability in aggressive environments and proposed cytocompatibility makes them an attractive material for fabrication of bi...
High temperature Na2O vapor conversion of α-Al2O3 with different concentrations of yttria stabilized zirconia (YSZ) was used to produce Na-β″-Al2O3 solid electrolyte (BASE) materials. The influence of different ratios of yttria (YSZ-3 and YSZ-8) on conversion and material properties (ionic conductivity and flexural strength) was also investigated....
Large diameter (> 100 mm) planar Na-β″-Al2O3 solid electrolytes (BASE) with thickness from 1.0 to 1.5 mm have been prepared. Na-β″-Al2O3 was processed as a slurry and cast to give several meters of tape. One hundred and forty mm diameter discs were punched from the tape, stacked, and laminated with a large hydraulic press. Binder burnout and sinter...
Tin‐based materials are an emerging class of Li‐ion anodes with considerable potential for use in high‐energy‐density Li‐ion batteries. However, the long‐lasting electrochemical performance of Sn remains a formidable challenge due to the large volume changes occurring upon its lithiation. The prevailing approaches toward stabilization of such elect...
In article number 1901220, Thomas Graule, Maksym V. Kovalenko, and co‐workers present a new synthesis of Sn nanoparticles (NPs) embedded in a SiOC matrix via the pyrolysis of a preceramic polymer as a single‐source precursor. This approach yields a homogeneous dispersion of Sn NPs in a SiOC matrix, which helps to buffer the volume changes of Sn and...
Ceramic foam materials have received great attention in recent years for their light weight, thermal/electrical insulation, high crack tolerance and good machinability properties. However, some applications demand higher mechanical strength, better resistivity of the surface against mechanical impact or improved abrasion resistance. In this paper,...
Freestanding SiCNO ceramic pieces with sub-mm features were produced by laser crosslinking of carbosilane and silazane polymer precursors followed by pyrolysis in inert atmosphere. Three different pulsed UV laser systems were investigated, and the influence of laser wavelength, operating power and scanning speed were all found to be important. Diff...
Pure torsional shear tests of joints glued with two different aerospace grade adhesives were performed using a specifically designed and constructed torsional shear test equipment. The developed test equipment allows for measuring of pure torsional shear strength under cryogenic and at elevated temperature conditions. The adhesives Hysol EA 9321 an...
Free standing single layer silicon carbonitride components with sub-mm features have been constructed by maskless lithography followed by pyrolysis. In comparison to prior fabrication methods based on molding of ceramic precursors, this work is advantageous as crosslinked polymer green bodies are formed in a direct manner and no mold is needed. The...
Polymer derived SiOC and SiCN ceramics (PDCs) are interesting candidates for additive manufacturing techniques to develop micro sized ceramics with the highest precision. PDCs are obtained by the pyrolysis of crosslinked polymer precursors at elevated temperatures. Within this work, we are investigating PDC SiOC ceramic monoliths synthesized from l...
The aim of the present work was changing the surface properties of alumina ceramic via sintering of samples in spinel MgAl2O4 and magnesia MgO powder bed. During sintering nitrogen and air atmosphere were used; and the reference material was sintered at the same conditions but in an alumina powder bed. All samples were sintered to a density higher...
With the aim of modifying the composition and microstructure of SiC and SiCN ceramics, we have investigated different reactive additives for polymer derived ceramic (PDC) precursors as well as changes in processing conditions (polymerization conditions, sintering conditions, etc.). Different concentrations of additive were dispersed in commercial c...
Up to now, commercially available alumina ceramics were claimed to have strength between 400 and 550. MPa. However, our study shows strength ∼ 2 times higher for commercially available alumina than commonly believed. The average and characteristic strength, measured on 31 pure alumina ceramic discs by ball on three balls (B3B) test, were 1205 ± 93....
The present work aimed with the carbon contamination in alumina ceramics and its influence on sinterability of alumina in low vacuum and atmospheres of argon and nitrogen. The commercially available alumina was coated with carbon and sintered at different atmospheres to investigate the effect of carbon presence on alumina sintering behaviour. The s...
The behavior of SiC ceramic joints brazed with commercially available Incusil ABA (Ag-32.25Cu-12.5In-1.25Ti, in wt.%) was characterized especially with respect to the mechanical performance at temperatures up to 550°C using four-point bending and torsional shear tests. The failure mechanisms with changing temperature were investigated with the aid...
Mechanical properties of tetragonal scandium-stabilized zirconium oxide (ScSZ) co-doped with cerium oxide are studied before and after a complete reduction of Ce4+ to Ce3+. Samples of 6Sc1CeSZ (i.e., 6 mol.% Sc2O3, 1 mol.% CeO2), 6Sc2CeSZ, and 4Sc1CeSZ are produced by pressure-less sintering in air at 1450 °C. Test pieces are annealed at 1200 °C in...
The introduction of lightweight cutting tips in industrial wood machining could lead to machining at much higher speeds and thus greatly increase efficiency. One possible way to achieve this is through lightweight ceramic composites. An Al2O3 ceramic matrix was selected and reinforced with particles resulting in a density of approximately one quart...
Aqueous silicon nitride based composite suspensions with the addition of 3.1 wt% of carbon nano-fibers (CNFs) were dried using two different drying techniques: spray drying and freeze drying. The paper deals with optimisation of parameters of the spray drying process with the aim of maximising the yield and improve the quality of the granulate. Fre...
Aluminum alloys are light-weight and one of the most interesting material solutions to optimize the strength/weight ratio to reduce car weight; however they are also relatively soft and therefore cannot be used for intensive wear applications. We developed an aluminum alloy part combined with hard and wear-resistant Al2O3-based ceramic plates on th...
Ceramic-based hollow spheres are considered a great driving force for many applications such as offshore buoyancy modules due to their large diameter to wall thickness ratio and uniform wall thickness geometric features. We have developed such thin-walled hollow spheres made of alumina using slip casting and sintering processes. A diameter as large...
Layered ceramic systems with designed stacks of dense and porous layers were investigated as alternative for thermal barrier protection system (TBPs). This approach gives the possibility to obtain low thermal conductivity with the impact protection of dense external layers whilst maintaining the relatively high mechanical properties. Different stac...
Active solder alloy 92Sn3Ag3Ti was used to join Al2O3 ceramic on cast A356 aluminum alloy substrate using anultrasonic assisted soldering process. Due to the large discrepancy in thermal shrinkage coefficients betweenmaterials, large thermal stresses occur during cooling down to room temperature. Further cooling to -78 °C and-196 °C was used to inf...
Laminated and subsequently sintered samples were prepared via aqueous (W_YSZ) and non-aqueous (E_YSZ) tape casting technique from fully stabilized zirconia ceramic powder. Preparation conditions optimised for the E_YSZ were implemented in a varied form to the W_YSZ and compared with each other. Namely the homogenisation time, rheological behaviour...
Ceramics are known to be chemically stable, and the possibility to electrically dope polymer-derived ceramics makes it a material of interest for implantable electrodes applications. We investigated cytotoxic characteristics of four polymer-derived ceramic candidates with either electrically conductive or insulating properties. Cytotoxicity was ass...
Laminated Al2O3 samples were prepared by tape casting and warm pressing of multiple layers into compact parts. The effect of a highly porous powder bed on the debinding process has been investigated by performing different debinding cycles with or without the powder bed. The effectiveness of the powder bed was analyzed using the concept of master d...
The effect of MWCNT introduction in a polycarbosilane based ceramic on its electrical properties is presented. The electrical conductivity of two MWCNT powders was measured under dynamic compaction up to 20 MPa when it reached 3–5 S/cm. The compaction behavior was also analyzed and modeled. A composite was then realized using allylhydridopolycarbos...
This paper describes a novel and scalable method for the fabrication of polymer derived ceramics (PDC) structures with high aspect ratio and micrometre scale features. Elastomeric micro-moulds composed of a filling pot are used to deliver via sacrificial micro-channels a precise amount of the liquid ceramic precursor to the target location with the...
An analysis about the effect of carbon enrichment of allylhydridopolycarbosilane SMP10® with divinylbenzene (DVB) as a promising material for electrical conductive micro-electrical mechanical systems (MEMS) is presented. The liquid precursors can be micropipetted and cured in polytetrafluoroethylene (PTFE) molds to produce 14 mm diameter disc shape...
A three phase ceramic composite consisting of a Si3N4 matrix reinforced with TiN and SiC particles was prepared by hot pressing. The Si3N4–TiN–SiC composite material was investigated for microstructure and mechanical properties. Dry wear tests were carried out and the results compared with two phase Si3N4–TiN and Si3N4–SiC composites. The Si3N4–TiN...
The utilization of silicon-based polymers as a source of amorphous non-oxide ceramics obtained upon pyrolytic treatment of them is increasingly gaining attention in research and is currently expanding into the field of commercial products. This work is focused on the near-net shaped fabrication, mechanical and tribological properties of a polymer-d...
Multi-wall carbon nano fibres (MWCNFs) offer an alternative to multi-wall carbon nanotubes (MWCNTs) as conductive reinforcing phases in ceramic composites. The main differences being their lower cost and larger dimensions. Alumina (Al2O3) composite materials with up to 12.5vol.% content of carbon nano fibres (CNFs) have been produced using standard...
Si3N4/SiC composites used for industrial wood cutting were processed by a near net shape route involving gas pressure sintering with sintering additives such as Al2O3, La2O3, Y2O3 and MgO. The cutting edge integrity of these knives was tested in a cutting trial and compared to knives made by a hot pressing route. It was found that the intergranular...
Cantilever structures from silicon nitride based composite ceramic materials were produced using laser cutting. A picosecond laser was used to cut two-dimensional meso sized cantilever structures up to 450μm thickness in conductive and insulating ceramics. A practical experimental based approach was used, where various parameters of the laser cutti...
This paper presents the failure of one particular design of component used in the production of ceramic bracelets for watches. A ceramic bracelet is made up of many ceramic “links”. The ceramic link components are interconnected using a metal skeletal frame to produce the bracelet. However, in service a number of the ceramic link components experie...
Si3N4/SiC cutting tools were fabricated by industrial near net shape fabrication processes. The samples were consolidated by gas-pressure sintering and pressure less sintering using three different additive systems. The mechanical and microstructural properties were compared to composites made by hot pressing. The composites fabricated by gas-press...
Zirconia/carbon nanofiber composites were prepared by hot pressing and spark plasma sintering with 2.0 and 3.3vol.% of carbon nanofibers (CNFs). The effects of the sintering route and the carbon nanofiber additions on the microstructure, fracture/mechanical and electrical properties of the CNF/3Y-TZP composites were investigated. The microstructure...
The fabrication method and the mechanical and electrical properties of different MoSi2–Si3N4 composite materials were investigated. Commercially available individual compounds, one-stage combustion synthesized MoSi2–Si3N4 and submicron MoSi2 powders were used as starting materials, followed by hot pressing. It was found that the sintering atmospher...
The effect of different sintering additives on the high temperature oxidation and corrosion behaviour of silicon nitride based ceramics was investigated. Comparative tests were conducted at 1200 and 1500 °C in air, in water vapour, and with the highly corrosive gases HCl and SO2. Si3N4 was prepared with MgO, Al2O3, Y2O3 and Al2O3 + Y2O3 sintering a...
Sintering and hot pressing have been used for preparation of monolithic ZrO2 and zirconia–carbon nanotube (CNT) composite. The effect of the processing route and the CNT's addition on the microstructure, fracture/mechanical and electrical properties of the zirconia has been investigated at room temperature. The microstructure of the sintered and ho...
The possibilities of the synthesis of submicron MoSi2 and MoSi2–Si3N4 composite powders were investigated using inorganic salt-assisted combustion synthesis method. Combustion laws in the MoO3–3Mg–2Si–NaCl and Mo–5Si–NaCl–Si3N4–N2 systems were studied. The main factors influencing the combustion parameters, phase composition and microstructure of p...
The effect of the addition of carbon nanofibers (CNFs) on the microstructure, fracture/mechanical and electrical properties of the CNF/zirconia composite has been investigated. The microstructure of both ZrO2 and ZrO2–CNF composites consists of a very low grain sized matrix (approximately 160 nm) with relatively well dispersed carbon nanofibers in...
The effect of different sintering additives on the high temperature oxidation and corrosion behaviour of Si3N4 ceramics is investigated. A corrosion furnace was set up which allows testing of ceramic discs at test temperatures upto 1500°C It was possible to conduct tests under ambient oxygen conditions, or with increased water vapour as well as tes...
The fabrication and properties of electrically conductive Si3N4–MoSi2 composites using two different sintering additive systems were investigated (i) Y2O3–Al2O3 and (ii) Lu2O3. It was found that the sintering atmosphere used (N2 or Ar) had a critical influence on the final phase composition because MoSi2 reacted with N2 atmosphere during sintering...
A process for the tape casting of silicon nitride ceramics has been developed and is described in detail. A solvent (ethanol) based recipe was developed using polyvinyl butyral and polyethylene glycol as the binder and plasticizer, respectively. The effect, of milling times, dispersant, solvent, plasticizer and binder contents were all investigated...
Electroconductive Si3N4–TiN composites were fabricated from micron-sized Si3N4 and nano-sized TiN powders by powder processing routes. The specimens were consolidated by hot pressing (HP) and spark plasma sintering (SPS). High densities (>98%) were obtained by sintering at temperatures ≥1500 °C using both sintering methods. The TiN phase grows rapi...
Silicon carbide particles have been introduced as reinforcements in a commercially available active metal braze filler alloy (Incusil ABA, Wesgo Metals) used for the joining of ceramic-to-metal. The effect of particle reinforcement of the braze filler on the flexural strength of ceramic to metal joints has been investigated at room temperature and...
The microstructure and mechanical properties of Si3N4–MoSi2 composites doped with two different sintering additive systems, Y2O3–Al2O3 and Lu2O3, were investigated. It was found that the composite doped with Y2O3–Al2O3 had an amorphous grain boundary phase, while the grain boundary phase of the Lu2O3-doped composites was completely crystallized. Th...
The possibilities for combustion synthesis of TiN–Si3N4 composite powders were investigated using different titanium silicides (TiSi, Ti5Si3, TiSi2) as initial raw materials. Thermodynamic analysis and relevant experiments have shown that at relatively low nitrogen pressure (up to 5 MPa) Ti5Si3 is the most suitable compound for this purpose. Optimu...