S. Salman

Microstructure and mechanical properties of friction stir welded particulate reinforced AA2124/SiC/25p–T4 composite

The purpose of the study is to present the feasibility of the joining of similar AA2124/SiC/25p–T4 composite plates by friction stir welding (FSW). Microstructure properties, microhardness, and tensile tests have been performed to evaluate the weld zone characteristics and the performance of AA2124/SiC/25p–T4 composite joints. The phase structure of a similar AA2124/SiC/25p–T4 composite weld was determined from X-ray diffraction (XRD). The temperature in the weld zone have been evaluated using thermocouples in order to demonstrate the FSWed joint of the AA2124/SiC/25p–T4 composite without melting. The obtained results revealed that FSW can be used in the joining of similar AA2124/SiC/25p–T4 composite plates. XRD measurements show that SiO2 phase was detected in the weld zones. It was determined that the peak temperatures achieved at 15 mm away from the weld center varied between 201°C and 270°C. In addition, the tensile strength of AA2124/SiC/25p–T4 butt joints was found to be approximately 20% lower than that of the base composite. The originality of this study is one of the preliminary studies on the detailed examination of the microstructural and mechanical properties of the AA2124/SiC/25p–T4 composite joint by FSW.

Effect of Sintering Temperature on Mechanical Properties and Microstructure of Sheep-bone Derived Hydroxyapatite (SHA)

Hydroxyapatite (HA) is currently one of the most attractive materials for human hard tissue implants because its close crystallographic resemblance to bones and teeth, conferring HA with excellent biocompatibility. Because of that fact as well as economic and time-saving reasons, we have stressed the need for safe production of HA-powders and ceramics from natural resources, such as animals’ bones and teeth, or hydrothermal transformation of shell’s aragonite.

Three types of ceramic coating applicability in automotive industry for wear resistance purpose

Purpose – The aim of the research is to investigate the influence of ceramic coating on the wear performance of machine parts.Design/methodology/approach – Ductile cast iron parts were coated using ceramics. Three ceramics were used for this purpose. These coated parts were subjected to wear tests under a stable load. A pin‐on‐disc wear test apparatus was used.Findings – As a result of this study, the following findings are reported: According to ASTM G 99‐90 pin‐on‐disc experiments, Cr2O3 was found to be best coating material with low wearing rate. Within row, Al2O3 and ZrO2 can be given. According to the previous work, motor parts for example piston ring, cylinder liner and engine valve can be coated with ceramic. In this study, it is observed that the figure of merit is increased in this study. Only wearing data is given in this research. The other results are also supporter of the results taken from the wearing experiments. As a result, due to the decrease in heat loss and coaling stability of part ca...

Studies of the correlation between wear behaviour and bonding strength in two types of ceramic coating

The plasma-spraying technique is used in this study. Two types of ceramic coating (Al2O3–13 wt% TiO2 and Cr2O3–5 wt% SiO2–3 wt% TiO2) with and without NiAl bonding coating are subjected to bonding strength and wear tests. Determining the most suitable coating and coating technique and solving an industrial problem are the main objectives of this study.

Reinforcing of Biologically Derived Apatite with Commercial Inert Glass

Apatite-based ceramics, derived from fine powder of calcinated bovine—bone (BHA), were successfully reinforced with 5 and 10 wt% commercial inert glass (CIG), which contained biocompatible elements, via sintering at different temperatures between 1000 and 1300°C. The products were subjected to mechanical testing and microstructural and crystallographic analyses. Comparison of the experimental results with those from earlier similar studies shows that CIG is superior for reinforcing of BHA ceramics compared with other bioactive glasses. Provided that the CIG addition does not exceed a certain limit, optimally being approximately 5 wt%, the resultant BHA-CIG materials can exhibit high strength after sintering and remarkable resistance toward over-firing at 1300°C. The influence of the amount of CIG on the developed microstructure and crystalline structure after sintering at different temperatures is discussed.

Sintering Effect on Mechanical Properties of Composites of Bovine Hydroxyapatite (BHA) and Li2O

In this study, hydroxyapatite (HA) material, obtained from calcinated bovine bone (BHA), was mixed with 0.25, 0.50, 1.00, and 2.00 wt% Li2CO3. The pressed pellets were sintered at various sintering temperatures between 900°C and 1300°C. Measurements of compression strength, microhardness, and density, along with SEM observation and X-ray diffraction analysis were performed. The experimental results showed that the samples with 0.25 and 0.50% Li2CO3 reached a maximum of densification and the highest values of compression strength and microhardness were achieved after sintering at 1300°C. The wetting effect of a Li2O-associated glassy phase was observed even from 900°C.

Sintering Effect on Mechanical Properties of Composites Made of Bovine Hydroxyapatite (BHA) and Commercial Inert Glass (CIG)

Composite biomaterials of calcinated bovine bone derived hydroxyapatite (HA) doped with 5 and 10 wt% commercial inert glass (CIG) were prepared by sintering. The production of HA from natural sources satisfies economic and time-saving aims, while the use of CIGs is directed by economic and ecological aspects. The produced composites were subjected to scanning electron microscopy (SEM) and X-ray diffraction analysis. Measurements of compression strength, microhardness, and density were also carried out. The experimental results and their discussion showed that the type and the composition of incorporated glass are of crucial importance. Consequently, provided that an optimum amount of glass is incorporated, the resultant materials can exhibit good values of compression strength and microhardness and hence they can be suggested for potential use in load-bearing biomedical applications.

Sintering Effect on Mechanical Properties of Composites of Bovine Derived Hydroxyapatite (BHA) with Titanium

The aim of this study was to prepare high performance biomaterials suitable for use at load bearing applications with high bioactivity. The hydroxyapatite (HA) was prepared from bovine bones via calcination technique. The bovine derived HA (BHA) was mixed with 5 and 10 wt% metallic titanium (Ti) and the obtained homogenous mixtures were pressed to produce the test samples. The compacts were sintered at temperatures between 1000 and 1300°C. Compression strength, density, and microhardness were measured. SEM and X-ray diffraction studies were also made. The best mechanical properties were obtained between after sintering at 1200-1300°C.

A Simplified Preparation Method of Silicon-Substituted Calcium Phosphates According to Green Chemistry Principles

A simplified preparation method of silicon-substituted calcium phosphates with a very high yield (close to 100%) has been elaborated, according to the principles of Green Chemistry. The technique consists of mixing of crystals of calcium nitrate and ammonium dihydrogen phosphate in the desired proportions, following by addition of the necessary amount of a silicon-containing compound. The homogenous mixture is sintered between 900 and 1200°C. Either a siliconcontaining hydroxyapatite (Si-HA) or a silicon-stabilized tricalcium phosphate (Si-αTCP) can be synthesized, depending on the Ca/P, Ca/(P+Si) and Si/P molar ratios.

The Influence of Sintering Temperature on the Properties of Composites of Biologic Hydroxyapatite and Zirconia

Bovine derived hydroxyapatite was doped with partially stabilized zirconia with 3 mol% yttria. The influence of sintering temperature and the amount of the incorporated zirconia on densification, mechanical properties, crystalline structure and microstructure was investigated. The results indicate that the produced materials exhibit poorer mechanical properties than the relevant composite materials of enamel derived hydroxyapatite. This difference can be attributed to F, since F-content in bone is much higher than in enamel. Hence, in the light of the prospective use of the investigated materials in biomedicine, bovine derived hydroxyapatite doped with zirconia can potentially serve as graft material for load bearing applications if very small amount of F can be incorporated, in order to resemble the composition of enamel derived apatite.