Jariah Mohd Juoi

Corrosion behavior of AZ91 Mg-Alloy coated with AlN and TiN in NaCl and Hank’s solution

Magnesium alloys create increasing interest in structural application where weight reduction is vast concern. However, its low corrosion resistance especially in atmosphere environment restricts their wide application. In this study, AlN and TiN were coated on AZ91 Mg alloy using PVD magnetron sputtering. AlN and TiN existence is confirmed via grazing angle x-ray diffraction (GA-XRD). The corrosion behaviors of uncoated and coated AZ91 Mg alloy in3.5% NaCl and Hanks solutions were investigated using a potentiostat during electrochemical corrosion test. AlN and TiN coated samples showed better performance in Hanks solution with TiN coated samples have the least corrosion rate (penetration rate=0.040mm/yr and mass loss rate=0.191g/m2d) in Hanks solution. These create interest to further works on exploring the potential of coated AZ91 Mg alloy in biomaterial application.

Characterization of TiAlBN Nanocomposite Coating Deposited via Radio Frequency Magnetron Sputtering Using Single Hot-Pressed Target

TiAlBN coatings have been deposited at varying bias voltage of 0, -60, and-150 V by radio frequency (RF) magnetron sputtering technique. A single hot-pressed Ti-Al-BN target was used for the deposition process. With glancing angle X-ray diffraction analysis (GAXRD), the nanocrystalline (nc-) (Ti,Al)N phase was identified. In addition, the existence of BN and TiB2 amorphous (a-) phase were detected by X-ray photoelectron spectroscopy (XPS) analysis. Thus, the deposited TiAlBN coatings were confirmed as nc-(Ti,Al)N/a-BN/a-TiB2 nanocomposite. On the other hand, it was found that optimum bias voltage used in present study is-60 V where the deposited TiAlBN coating exhibits an excellent adhesion quality. The adhesion quality of the coatings deposited at-60V bias voltage is classified as HF 1 evaluated using the Rockwell-C adhesion test method (developed by the Union of German Engineers).

Characterisation and Properties of Sintered Glass-Ceramics Produced from Recycling Glass by Using Pressure-Less Method

The aim of this research is to develop glass ceramic produced from recycling glass. Waste glass (e.g. container and bottles) of soda lime silica (SLS) glasses is utilised as main raw materials for the formulation of glass ceramic batch composition with the addition of ball clay. The ball clay was added in order to favour shaping. The recycled glass powder are then mixed with the ball clay according to the ratio of SLSG to ball clay of 95:5 wt.%, 90:10 wt.% and 85:15 wt.%. Differential Thermal Analyses (DTA) was carried out in order to determine the thermal characteristic glass powder prior to the batch formulation. The glass was then crushed, milled and sieved to < 75µm and mixed with the ball clay before it was pressed to a pellet by pressure-less method. This pressure-less route is conducted as an approach to a simple fabrication route of the glass-ceramic samples. The green samples are then sintered at different temperature. The dense and strong glass ceramic samples were obtaining at 850oC, with holding time of one hour and morphological characterized with X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analyses. Results shown that glass ceramic samples produced at this optimized sintering profile had high density and microhardness value with low porosity and negligible water absorption. Overall results indicates that glass ceramic samples have good mechanical properties (e.g. microhardness exceeding 700Hv) and physical properties (e.g. water absorption, density, porosity making them attractive to the structural application. These results are also utilised as a comparison to a glass ceramic samples produced via Cold Isostatic Press (CIP) from the same batch composition formulation and sintering profiles for the purpose of optimizing the waste glass utilization.

Development and characterization of charcoal filled glass-composite materials made from SLS waste glass

Glass-composite materials were prepared from the soda lime silicate (SLS) waste glass, ball clay and charcoal powder at various carbon content, of 1wt. % C, 5wt.% C and 10 wt.% C, fired to temperature of 850 °C as an alternative method for land site disposal method as well as effort for recycling waster glass. The effect of charcoal powder on the porosity, water absorption and hardness properties were studied. Phase analysis studies revealed the present of quartz (ICDD: 00001-0649, 2θ = 25.6° and 35.6°), cristobalite (ICDD 00004-0379, 2θ = 22.0° and 38.4°) and wollastonite (ICDD 00002-0689, 2θ = 30.1° and 26.9°). The results showed that the composite prepared from the mixture of 84 wt.% SLS, 1 wt.% of charcoal and 15 wt.% ball clay containing average pore size of 10 µm has projected optimized physical and mechanical properties. It is observed this batch has projected lowest water absorption percentage of 0.76 %, lowest porosity percentage of 1.76 %, highest 4.6 GPa for Vickers Microhardness.

The Influence of the Microwave Plasma Nitrided Ti6Al4V Substrate Properties to the Duplex Coating Performance

Titanium alloys, especially TI6Al4V has been used in many industries such as aerospace applications, medical application and automotive applications. This is because it has beneficial properties such as low density, high strength to weight ratio, low modulus elasticity, excellent corrosion resistance and etc. However, titanium and its alloys have limited use in mechanical engineering applications involving sliding wear or abrasion due to poor wear resistance. Therefore, the duplex coating concept was introduced with the intention of the surface modification process as a pre-treatment of the substrate prior to the deposition of hardcoating process. In this study, plasma nitriding of the Ti6Al4V was performed using a microwave plasma technique at 600°C and 700°C for 1 hour, 3 hours and 5 hours, then followed by deposition of chromium nitrate (CrN) on plasma nitrided samples for duplex coating purposes. Microstructural analysis and mirohardness measurement revealed that formation of Ti2N and TiN phase indicating the formation of the compound layer was observed for substrate nitrided at temperature as low as 600°C for 1 hour and a substantial increase on the case depth obtained on plasma nitrided Ti6Al4V was observed with an increase of process temperature and time. The duplex coating obtained in this study has superior surface hardness property and improved load carrying capacity of the coating – substrate system compared to CrN coatings deposited on as received Ti6Al4V which was observed in the penetration depth analysis.

Physical and Mechanical Properties of Glass Composite Material Made from Incinerated Scheduled Waste Slag and SLS Waste Glass

Incineration of scheduled waste and landfilling of the incineration residue (Bottom Slag) is extensively practised in Malaysia as a treatment method for scheduled waste. Land site disposal of Bottom Slag (BS) may lead to environmental health issues and reduces the availability of land to sustain the nations development. This research aims in producing Glass Composite Material (GCM) incorporating BS and Soda Lime Silicate (SLS) waste glass as an alternative method for land site disposal method and as an effort for recycling SLS waste glass .SLS waste glass originates from the urban waste and has been a waste stream in most of the nation whereby the necessity for recycling is in high priority.The effect of BS waste loading on the GCM is studied.Batches of powder mixture is formulated with 30 wt% to 70 wt % of BS powder and SLS waste glass powder for GCM sintering.The powder mixtures of BS and SLS waste glass is compacted by uniaxial pressing method and sintered at 800C with heating rate of 2C/min and 1 hour soaking time. Physical analysis of bulk density, apparent porosity, and water absorption is perfomed according to ASTM C-373 standard. Mechanical testing of microhardness vickers according to ASTM C1327 and Modulus of Rupture (MOR) according to ISO 10545-4 is conducted. Microstructural analysis is carried out using Scanning Electron Microscope and phase analysis by X-ray diffraction method.Phases identified are Anorthite sodian,Quartz,Hematite and Diopside from X-ray diffraction analysis. Higher BS waste loading shows weak physical and mechanical properties .GCM from batch formulation of 30 wt % BS and 70 wt% SLS waste glass has projected optimized physical and mechanical properties. It is observed this batch has projected lowest water absorption percentage of 1.17 % , lowest porosity percentage of 2.2 %, highest bulk density of 1.88 g/cm3 and highest MOR of 70.57 Mpa and 5.6 GPa for Vickers Microhardness.

Effect of Calcination Temperatures on Phase Transformation and Stability of β-Tricalcium Phosphate Powder Synthesized by a Wet Precipitation Method

Beta-tricalcium phosphate (β-TCP) was never synthesized directly using an aqueous method. As-precipitated powder from a wet chemical method needs to undergo a heat-treatment process (or calcination) to enable the intermediate phase (s) to be transformed into single-phase TCP. In this work, calcium hydroxide, (Ca (OH)2), and phosphoric acid, (H3PO4), were mixed as the precursor materials with a Ca/P ratio of 1.5,. The mixture was stirred at a fixed stirring speed of 200 rpm and a stirring duration of 2 hours. The precipitate thus obtained was filtered and dried overnight before being tested by differential scanning calorimetry and thermogravimetry (DSC/TG) up to 1300°C for thermal behaviour upon firing. The powders were then calcined at various temperatures (500°C, 700°C, 900°C 1000°C, 1100°C, 1200°C and 1300°C) for a duration of 2 hours. The calcined powders obtained were analysed by x-ray diffraction (XRD) to determine the transformation of phases. Monetite and hydroxyapatite were the phases detected after calcination at 500°C and 700°C, whilst at a temperature of 900°C up to 1300°C, only a single phase β-TCP was observed. Microstructural observation by scanning electron microscopy (SEM) was conducted on the β-TCP powders obtained at calcination temperatures of 900°C to 1300°C. The results showed a massive crystal growth of the aggregated particles, but even so, the phase remained stable as monolithic β-TCP.

The Effect of Spent Bleach Earth on the Properties of Sintered Green Glass Ceramic Composite

The purpose of this study is to investigate the effect of spent bleach earth (SBE) loading on the properties of green glass ceramic (GGC) composite. GGC was prepared using SBE and recycled soda lime silicate (SLS) glass. SLS glass was crushed then sieved to approximately 45µm. These GGC composites were formed with different weight fraction of SBE loading (40, 45 and 55 wt.%) by uniaxial dry pressing and sintered at different sintering temperature (700 °C, 750 °C and 850 °C). The sintering temperatures were selected based on Tg of the glass which is around 416 °C. The GGC specimens were analyzed in terms of its physical properties (density, water absorption and porosity), phase presence (X-Ray diffraction) and sintered microstructure (scanning electron microscopy). X-Ray diffraction pattern indicated that cristobalite, quartz and wallastonite phases were formed during sintering. It was found that the GGC with 45 wt.% of SBE loading sintered at 850 °C produced minimum water absorption which was 4.01% accompanied by density of 2.12 g/cm3 and a porosity of 8.49%. This shows that GGC composite produced with considerable higher amount of waste loading able to obtain acceptable physical durability.

Effect of Dipping Numbers on the Crystalline Phase and Microstructure of Ag-TiO2 Coating

Sol-gel dip-coating technique was utilized to prepare Ag-TiO2 coating with additive (Degussa P25) on unglazed ceramic tiles. Three different numbers of coating layers (5, 7 and 10 layers) were deposited on unglazed ceramic tiles made of waste glass. The coatings were sintered at 500 °C with the heating rate of 2 °C/min. The crystalline phase and cross sectional areas of the coatings were evaluated using GAXRD and SEM analysis, respectively. Results showed that the average thickness of the coating increased from 7 µm to 9 µm and to 12 µm for 5, 7 and 10 coating layers, correspondingly. Coating of 10 layers exhibited a high crystallinity of anatase phase, a good surface morphology without significant cracks, and a homogeneous coating compared to the 5 and 7 layers of coating, which suggested a better performance in Ag-TiO2 coating.

Effect of Additives on the Characteristic of Ag-TiO2 Coating Deposited on Specially Made Unglazed Ceramic Tile

In this research, the effect of PEG 2000 and Degussa P25 as additives on the characteristic of Ag-TiO2 coating was reported. The TiO2 coatings were produced via sol gel method using titanium (IV) isopropoxide (TTiP) as a precursor from solutions that contains additive and without additive. Seven layers of TiO2 coating were deposited on specially made unglazed ceramic tiles produced from waste glass. All coatings were deposited using dip coating technique and were sintered at 500 °C. The TiO2 coating was then immersed in an Ag nanoparticles solution before dried at 90 °C in an oven to form Ag-TiO2 coating. The coating phases and coating morphologies were analyzed using GAXRD and SEM analysis, respectively. Results show that Ag-TiO2 coating added with Degussa P25 additive exhibits a presence of more anatase and more homogenous microstructure which gives advantages for antimicrobial application as compared to others