Mariyam Ghazali

National University of Malaysia | ukm

This study aimed to evaluate the influence of particle size and pre-sintering temperature on the mechanical properties of pre-sintered monolithic zirconia blocks. Zirconia blocks were fabricated using two types of zirconia 3YSZ powders: one with a particle size of 20-nm (20 nmZ) and another with a particle size of 60-nm (60 nmZ). The blocks were pr...

Al–5.7Si–2Cu–0.3Mg alloy was subjected to a thixoforming process. The impact behaviour of the thixoforming process on microstructure characterisation and mechanical properties was investigated. A cooling slope (CS) technique was applied here to get thixoforming feedstock material at three different pouring temperatures of 640 °C, 650 °C and 660 °C,...

The aim of this work is to investigate the optimum heat treatment for Al-5.7Si-2Cu-0.3Mg aluminium alloys and study its effect on microstructure, phase transformations, and hardness. The test specimens were taken from the as-received alloy. Solution treatment was performed at 485•C and 500•C under various solution treatment times for 4, 8, 10, and...

This study aimed to investigate the colloidal stability of (Cu,Mn,Co)3O4 spinel in various suspension media and suitable applied voltage for electrophoretic deposition (EPD). The performance of the coated SUS430 was evaluated in terms of oxidation behaviour, Cr migration and electrical conductivity. The (Cu,Mn,Co)3O4 suspension prepared using a mix...

TiC0.7N0.3 is widely used as a cutting tool and an abrasion-resistant material for operations requiring high wear resistance and strength. In this study, we attempted to solve one of the main issues in TiC0.7N0.3; synthesis at high temperature (>1000 °C). The use of NH4NO3 powder was put forward for the first time as a precursor to supply N2 gas fo...

Present work focused on the impact of high temperature on the tribological properties for thixoformed Al-5.7Si–2Cu-0.3 Mg alloy. A pin-on-disc tribometer was used for dry sliding wear experiments that were executed according to Taguchi method. Wear behaviour was investigated under four process parameters at three levels: process (as-cast, thixoform...

Titanium carbonitride (TiCN) is a popular hard coating for carbide cutting tools in various applications. The properties of TiCN are within its composition and can be controlled by maintaining the C–N ratio within the coating to a certain level. This paper studied the influence of carbon content and coating composition within TiCxN1−x coatings with...

Titanium carbonitride (TiCN) is a popular hard coating for carbide cutting tools in various applications. The properties of TiCN are within its composition and can be controlled by maintaining the C-N ratio within the coating to a certain level. This paper studied the influence of carbon content and coating composition within TiC x N 1−x coatings w...

In this study, the effect of improved microstructure of Al-5.7Si-2Cu-0.3Mg alloys by using semisolid process on hardness and dry sliding wear behaviour were investigated. The microstructures of conventional cast alloy were totally dendritic, while in rheocasting the dendritic transfer to fine globular microstructures after using cooling slope casti...

In this study, the effect of improved microstructure of Al-5.7Si-2Cu-0.3Mg alloys by using semisolid process on hardness and dry sliding wear behaviour were investigated. The microstructures of conventional cast alloy were totally dendritic, while in rheocasting the dendrit-ic transfer to fine globular microstructures after using cooling slope cast...

A rapid and simple method for Ag2O–CuO nanocomposite synthesis is developed via the microwave-assisted reduction of Ag and Cu ions in an aqueous solution at different molar ratios of precursor. This study aimed to determine the effects of the chemical composition on the microstructure and antibacterial properties of the materials. X-ray diffraction...

One of the most compatible coatings, known as yttria-stabilised zirconia polycrystal (YZP) is deposited on metallic Ti alloys due to its excellent hardness and aesthetic value as well as its low affinity for plaques. However, poor bioactivities of YZP and the existence of micro crack propagations due to the aging of YZP may result in spontaneous im...

Understanding zirconia 3YSZ powder dispersion is crucial in achieving colloidal stability in order to produce high-strength and translucent structures required for dental applications. In this work, pH adjustment (pH 1-11) and mechanical treatment (ball milling, ultrasonic treatment, and centrifugation) were employed to remove agglomeration. As-rec...

In this paper, the techniques for the synthesis of CaFe2O4 nanoparticles using the auto-combustion and co-precipitation methods are discussed. The effects of both methods on the microstructure and magnetic properties of the CaFe2O4 nanoparticles were compared. The CaFe2O4 powder was obtained after drying the synthesized sample via co-precipitation...

A series of Al–6Si–3Cu–(0.3–2)Mg alloys were produced by a conventional casting process. Cooling slope technique was employed to produce feedstocks before they were thixoformed at 50% liquid fraction. The effect of Mg on the microstructure of Al–Si–Cu aluminium alloys under as-cast and semisolid conditions was investigated. It was found that by add...

Calcium ferrite (CaFe 2 O 4) nanoparticles using calcium nitrate and ferric nitrate as starting materials, and supplemented with citric acid as chelating agent was carried out. This mixture was synthesized through a sol-gel method and then calcined at 550 °C, 650 °C, and 750 °C. The effects of calcination temperatures on the crystalline structure,...

Most of the structural components in real applications are subjected to variable amplitude loading. The load sequence may have a significant effect on the number of cycles to failure. However, the relationship between the mechanical behaviour of material and the load sequence effects has scarcely been reported. Therefore, this paper discusses the i...

Recently, natural fibers become an attractive to automotive industry as an alternative reinforcement for glass fiber reinforced thermoplastics. Additionally, natural fiber components in the automotive industry can provide numerous advantages compared to synthetic conventional such as reduction of weight and cost, recyclability, renewability and in...

This study was aimed at investigating the effects of micro-grooves on the tribological behaviour of a plasma-sprayed Al2O3 − 13%TiO2 coating. A combined surface profile with non-regular depths and micro-groove texture was successfully developed by using a Nd:YVO4 laser system. The surface condition and characterisation of the Al2O3 − 13%TiO2 coatin...

This paper numerically discusses the role of J-integral along the surface crack front in cylindrical bar under combined mode I loading. It is also verified the analytical model derived from the first part of this paper by comparing the results obtained numerically using ANSYS finite element program. It is found that the proposed model capable to pr...

In this study calcium ferrite nanoparticles are synthesized using a sol-gel method and the magnetic properties of these nanoparticles are characterized. The influence of process parameters, namely molar ratio of starting materials, calcination temperature and effect of polyvinylalcohol (PVA) on particles size is also investigated. These parameters...

This paper reviews the previous literature on the effects of loading sequence on fatigue life behaviour. Through load interaction, load sequences can significantly affect fatigue life. The study on fatigue life under spectrum loading sequence is complex because it involves many interaction parameters. Therefore, the experimental and simulation find...

Materials with well-defined surface structures are prepared using protective coatings through surface texturing, which is a novel method for modifying surface characteristics, particularly tribological and wettability, to improve the properties of material parts. The formation of a specific patterned surface can be achieved through abrasive blastin...

Wear is one of the common degradations in a commercial gas turbine. A stainless steel grade 304 (SS 304) fuel nozzle and its collar made of nickel-based superalloy (Hastelloy X) are two vital components that normally suffer from rapid wear. During an installation, the fuel nozzle is slotted into the collar of the combustion liner. In operation, the...

In this study, the dry sliding wear characteristics of Al–6Si–3Cu–(0.3–2) Mg–aluminium alloys produced by the thixoforming process were examined. The cooling slope technique was employed to produce feedstock alloys before they were thixoformed at 50% liquid fraction. A pin-on-disc rig was used to carry out the wear tests at 50 N load, 1 m/s speed a...

In recent years, ceramic coating with well-defined surface structures have been prepared in order to combine the advantages of protective coatings and the beneficial effects of surface texturing. Surface texturing is a new way to modify surface characteristic that lead to an improvement in properties of material parts particularly for tribologic...

The properties of titanium carbonitride (TiCN) are a result of its composition, which can be adjusted by controlling the material’s C-N ratio to a precise level. An experimental study was conducted to vary the composition and properties of TiCN. The substrate used for cathodic arc physical vapour deposition (CAPVD) was tungsten carbide (WC-6Co), wh...

The effect of magnesium addition on dry sliding wear characteristics of thixoformed Al-Si-Cu aluminum alloy was investigated. A pin-on-disc tribometer was used to carry out wear tests at 49N, 1m/s speed and 9Km distance. It was observed that increasing in Mg content up to 1.5 wt.% improves wear resistance and hardness of the thixoformed alloys. Add...

The calcium ferrite nano-particles (CaFe2O4 NPs) were synthesized using a sol-gel method for targeted drug delivery application. The proposed nano-particles were initially prepared by mixing calcium and iron nitrates that were added with citric acid in order to prevent agglomeration and subsequently calcined at a temperature of 550°C to obtain smal...

This review covers several basic methodologies of surface treatment and their effects on titanium (Ti) implants. The importance of each treatment and its effects will be discussed in detail in order to compare their effectiveness in promoting osseointegration. Published literature for the last 18 years was selected with the use of keywords like tit...

The microstructural and dry sliding wear characteristics of thixoformed A319 aluminium alloy are investigated and compared with those of a conventional mould cast alloy. Cooling slope technique was employed to produce thixoforming feedstock with pouring temperatures between 620 and 640 C, plate lengths between 300 and 500 mm and 60 inclined angle....

Many studies were carried out to investigate the ability of titanium alloys for dental implant. Surface treatment is one of the famous methods to increase the titanium surface properties. The purpose of this paper is to investigate the effects of acid etching on the surface topography and roughness of titanium alloys (Ti6Al4V ASTM 1472-99). Acid et...

With good combination of hardness, ductility, and wear resistance, TiO2 coatings are one of the most potential hard ceramic coatings. TiO2 in an Al2O3 coating had increases the wear resistance which has contributed to an increase in the fracture toughness and decrease in the coefficient of friction. The specific wear rates of pure TiO2 coatings are...

In the last five years, UKM has been very active in promoting research and development activities after being selected as one of the leading research institutions in the country. Postgraduate students enrolment has been increasing since, but it was perceived that a very low percentage of UKM undergraduate students have registered into postgraduate...

The traditional steps in the fabrication of Malay Keris blades which are preserved in traditional knowledge are explained in consistency with the modern metallurgical engineering. These are forging, quenching, tempering and etching. The material selection process for specific parts of the blade is discussed and correlated to the particular fabricat...

The aim of this paper is to investigate the influence of the second phase morphology (TiC) on wear behavior in Fe-TiC composites. Fe-TiC composites were successfully produced by an in-situ melting method under an inert argon gas in which raw materials, namely cast iron (Fe-3.5wt%C) and 10wt%ferrotitanium (Fe-72wt%Ti) were used. The obtained melting...

Zirconia-based dental ceramic is widely used for crown restoration, because of its superior mechanical properties and favorable biocompatibility. However, yttria-stabilized tetragonal zirconia (3YSZ), which is used in most dental crown restorations, has low translucency. This characteristic is unfavorable and results in low aesthetic quality of den...

Cermets, particularly those based on TiC, are receiving considerable attention because of their unique properties, including high hardness and resistance to thermal deformation. However, TiC-based cermets lack sufficient toughness. To improve the performance of these cermets, numerous studies have been conducted to determine the factors that can be...

This paper explains about an improvement of high end performance using an adaptive valve lift and timing mechanism (AVLT). This system is developed with an aim to produce a more powerful engine through a variable valve timing technique. The preliminary design of this system adjusts the valve lift via control lever positioned by the rotation of an e...

Compressed natural gas with direct injection (CNGDI) engine produces high temperature and pressure ultimately leading to high thermal stress. The piston crown material fails to withstand high temperature and operate ineffectively due to improper heat transfer. By insulating the surface namely; thermal barrier coating (TBC) such as ceramic based ytt...

Poly(methyl methacrylate) (PMMA) is an extensively used material in dentistry because of its aesthetics, processability, and reparability. However, PMMA is still far from being ideal in fulfilling the mechanical requirements of prosthesis. PMMA-based denture base polymers exhibit low fracture resistance and radiopacity behavior. Efforts to improve...

This paper discusses the effects of plasma spray parameters on the mechanical properties of nanostructured TiO2 coatings deposited on mild steel substrates. The design of experiment method was applied to investigate the significant effects of each property and to optimize the operational spray parameters. Plasma power, powder feed rate, and stand-o...

The stability of nano-zirconia 3YSZ powder in suspension was extensively studied by the colloidal method, and the optimum sintering temperature of the green sample fabricated through slip casting was determined. Zirconia suspensions with 10 vol% powder loading were prepared with distilled water, and HNO3 was used to adjust the pH of the suspension...

Fracture mechanics approach has successfully used to characterize the existing cracks in engineering materials and structures. Tremendous number of publications on surface cracks can be found for crack behaviour which was assumed to behave linear elastic. However, lack of information on elastic-plastic crack behaviour or J-integral was demanded esp...

This paper discusses the fatigue strain signal behaviour of different road surface conditions and its relationship to the fatigue damage of an engine mount bracket. Two different sets of fatigue strain signals were obtained from an engine mount bracket of an automobile: when the automobile was driven on a highway surface and on a residential area r...

Consolidation of ceramic parts may be achieved by several techniques, including the slip casting and cold isostatic pressing (CIP) methods. In the present work, the performances of the two methods are compared in the fabrication of nanostructured zirconia compacts for dental crown applications. First, a zirconia suspension suitable for slip casting...

Zirconia-based ceramics exhibit excellent mechanical properties and biocompatibility in dental applications. However, the production of translucent zirconia that offers resemblance to real teeth remains a challenge. This study aims to fabricate zirconia compacts by cold isostatic pressing (CIP) and investigate the influence of sintering temperature...

High temperature produced in a compressed natural gas with direct injection system (CNGDI) engine may contribute to high thermal stresses. Without appropriate heat transfer mechanism, the piston crown would operate ineffectively. In this work, bonding layer NiCrAl and ceramic based yttria partially stabilized zirconia (YPSZ) were plasma sprayed ont...

Yanbu Industrial College (YIC) is one of the leading technical colleges in Saudi Arabia offering associate degree and bachelor degree programs in engineering and applied sciences. As a technical college, the approach of teaching is predominantly classical with theoretic lectures and hands-on experimental/laboratory works. Course assessment was heav...

This paper explores the Masters of Mechanical Engineering students’ perceptions on Research Methodology course, which has been introduced in 2010 in the Department of Mechanical & Materials Engineering, of Universiti Kebangsaan Malaysia (UKM). The course is only available for students who register KKKJ 6004 (Project 1) in the first semester, which...

All-ceramic dental crown restoration is popular because it results in better aesthetic quality than metal alloy restoration. Ceramics also show superior biocompatibility and inertness to human biological systems. However, clinical experience indicates that all-ceramic crowns are not as durable as their porcelain-fused-to-metal counterparts, particu...

The effect of solute Cu and Cu precipitates on the wear behavior of ferritic iron under an unlubricated condition was investigated. The specific wear rate of Cu-containing steel abruptly decreased up to 50 N of load, and then gradually decreased with further increased load. The specific wear rate of the as-quenched specimen, in which Cu was in a so...

Numerous methods have been well developed in the area of bearing monitoring. This paper presents an experimental study of wear monitoring of connecting rod bearings type AA7075-T6 within audio frequency signals; f<20 kHz against a AISI4340 hardened steel via air-borne with the aid of tribometer. The objective of this study is to determine the corre...

Due to high temperature and less proper heat transfer, the material of piston crown in an engine of compressed natural gas with a direct injection system (CNGDI) may lead to high thermal stresses and fails to withstand high temperature and operate effectively. By insulating with thermal barrier coating (TBC) such as ceramic-based yttria partially s...

The study aimed to present several fatigue tests under loading sequences, and to compare the fatigue life behaviour between AA6061 and AA7075 alloys subjected to spectrum loadings at room and elevated temperatures. Constant amplitude loading (CAL), high-to-low and low-to-high loading sequences were derived from a real-time variable amplitude loadin...

This paper discusses a methodology used to predict the stress-life (S-N) curve at elevated temperatures based on the normal S-N curve. Fatigue tests were performed under stress control at room temperature in accordance with the ASTM E466 standard to obtain a normal S-N curve. In addition, the tests were performed at both room and elevated temperatu...

This paper discusses the fatigue life behaviour of aluminium alloy AA6061-T6 under spectrum loadings. Load sequences in spectrum loadings can have significant effects on fatigue life at room temperature and within the elevated temperature range. The main objective of this paper is to investigate the influences of load sequences effect on fatigue li...

In this study, A356/Al 2 O 3 metal matrix composites were fabricated by conventional stirring and semisolid processing (combination of mechanical stirring in the mushy zone and cooling slope casting) and these composites were subjected to wear tests. The composites containing various weight fractions of Al 2 O 3 particles (1%, 2.5% and 5%) were use...

This study focuses on the effects of powder size and Ni–Al bonding layer on the electrochemical behaviour of plasma-sprayed Al2O3-13% TiO2 coating in fresh tropical seawater. The presence of the metallic bonding layer reduces the coating porosity and increases the surface roughness for both microparticle and nanoparticle coatings. The nanoparticle...

This paper explains about the evaluation of intake air flow, volumetric efficiency and noise of a motor-driven engine that used an adaptive valve lift and timing mechanism (AVLT) on one intake valve. This system is developed with an aim to produce a more powerful engine through variable valve timing and lift technique. The system made the valve lif...

High temperature and pressure produced in an engine of compressed natural gas with a direct injection (CNGDI) system may lead to high thermal stresses. By insulating the piston crown using a thermal barrier coating (TBC) such as ceramic-based yttria partially stabilised zirconia (YPSZ), the heat transfer of the piston might be reduced and lead to a...

In this study, a design of experiment (DoE) method was utilised to identify the effect of air plasma spray (APS) parameters on several main properties of titanium dioxide (TiO2) coatings. Titanium dioxide (titania) feedstocks with sizes ranging from 10 μm to 45 μm were sprayed onto the mild steel substrates with different plasma spraying parameters...

Semi-metallic friction composites (SMFC) consist of epoxidised natural rubber with 50 mol % epoxidation (ENR50), alumina nanoparticle, steel wool, graphite and benzoxazine were prepared by melt mixing using Haake internal mixer at 90°C and 60 rpm rotor speed. The composites were vulcanized using different crosslinking systems, namely, sulfur and el...

This study aims to evaluate the effects of sintering temperature on the density and hardness of tetragonal zirconia polycrystals stabilized with 3 mol% 3Y-TZP dental ceramic type. Five cylindrical specimens were fabricated from zirconia powder of particle size 50 nm via colloidal processing. The specimens were sintered densely at the final sinterin...

Coating a cutting tool improves wear resistance and prolongs tool life. Coating performance strongly depends on the mechanical and chemical properties of the coating material. In a machining process, the type of selected coating depends on the cutting condition because of the properties of the applied coating material. In addition, many factors, su...

Purpose The purpose of this paper is to study the wear behaviour of eutectic and hypoeutectic Al‐Si‐Mg‐Ce alloys. Design/methodology/approach The eutectic and hypoeutectic alloys were prepared using permanent mould casting process by varied cerium (Ce) addition in the alloy from 1 to 3 wt%. Dry sliding wear tests were performed against a hardened...

This study presents a numerical investigation on the stress intensity factors (SIF) obtained under pure torsion loadings or mode III. ANSYS finite element analysis (FEA) was used to determine the SIFs along the crack front of surface cracks embedded in the solid circular bars. 20-node isoparametric singular elements were used around the crack tip b...

The effects of a polyelectrolyte dispersant agent, polyethyleneimine (PEI), on the rheology of zirconia 3Y-TZP suspensions and the densification characteristics of sintered zirconia were investigated. The colloidal processing technique was used to minimize the agglomeration of nanoparticles during the fabrication of the samples. Five batches of 10%...

The purpose of this work is to understand the phases formation and lattice parameter changes with addition 0.6 to 2.7 wt.% in Al-Si-Mg-Ce cast alloy. Al-Si-Mg-Ce eutectic and hypoeutectic cast alloy were prepared by conventional casting technique. The alloys were investigated by using optical microscope, Scanning electron microscope (SEM) and X-Ray...

The development of dental crowns is highly concerned with optimum mechanical properties, superior esthetic appearance and biocompatibility. In order to meet these requirements, structural ceramics have been improved and have become increasingly more popular in dentistry. Among the dental ceramics, zirconia is the dental restorative material most co...

AA6063 alloy is a common materials used in boat and ship construction due to its lightweight and good strength. However, its strength is lower than steel's strength. For that reason, an improvement in strength is needed. In this work, an attempt has been made to improve the tensile strength of AA6063 alloy by adding manganese (Mn) element. From 0.5...

This paper presents an assessment on fatigue crack propagation (FCG) behavior and fractography observation for an aluminum alloy that was exposed under spectrum loadings. The FCG test has three types of cyclic loadings, namely, constant-amplitude loading (CAL) as well as high-to-low and low-to-high sequence loadings. All three have been performed o...

This paper explains the effect of various lubricant and engine temperatures on the intake mass air flow, engine noise and lubricant pressure behaviour of a motor-driven spark ignition engine. The lubricant pressure, engine noise and mass air flow changes were recorded under a steady state operating condition with an increased engine speed in which...

This paper discusses the effect of plasma spray parameters of deposited agglomerated nano Al2O3-13%TiO2 powders on commercial marine-grade mild steels. Prior to the coating work, the nanopowders were subjected to a two-level factorial design of experiment to optimize the operational spray parameters, namely, the primary gas pressure, the carrier ga...