This paper reports on the compatibility of hydroxyapatite (HAP) combined with single based binder, palm stearin for ceramic injection molding in order to obtain the best properties. The feedstock was prepared at a powder loading of 62 Vol % using 5μm fine ceramic powder of hydroxyapatite and the binders consisting of 100% of palm stearin. The specimens underwent thermal de-binding and then sintered in an electrical furnace within a temperature range from 500°C to 1000°C. The resulting exhibit promising properties which the final product produced after the sintering process was successfully tested by mechanical testing. It is proven that even the specimen only consists of single based binder can form a complex shape without collapse just like the specimen obtained by the conventional binder system. Therefore, the fabrication also is more towards green processing technology and energy conservation due to the binder used was from natural local resources and used lower processing temperature at 50°C to 70°C for mixing and injection molding.
Zirconia and alumina are one of the materials that is widely used in medical industry. Zirconia Toughened Alumina (ZTA) have great properties to be apply in the ceramic injection molding such as have high hardness and high strength. The powder used in this research are alumina and zirconia while the binder to be used in this research is using 100% single based binder of palm stearin (PS). Behavior of zirconia blended alumina was investigated by rheological testing at temperature 55°C. Two formulations were used which is 60% (alumina/zirconia) plus 40% PS and 64% (alumina/zirconia) plus 36% PS. The ratio of alumina and zirconia used in this research is fixed at (85:15) for both samples. Four basic process involved which is mixing process, injection molding, thermal debinding and sintering process has been implemented to complete ceramic injection molding (CIM). Sample were performed the thermal debinding at a heating rate 0.5°C/min up to 700°C and sintering at heating rate 3°C/min for temperature 1400°C and 1600°C. The hardness was tested using Rockwell hardness test for both AZ60 and AZ64 sample. Highest hardness was obtained from the sample AZ64 at the temperature 1600 °C which is 109HRR compare to the 1400°C that achieved 95.3HRR.
This study presents the effects of sintering temperature and binder content of polyethylene glycol (PEG) on wear properties of compacted alumina using pin on disc wear test under dry sliding condition. Wear rate was measured at 20N load and sliding speed of 200rpm at 0.28 m/s sliding velocity. The wear test sample was tested at 3 different sintering temperatures (1000°C, 1100°C, and 1200°C) to produce different microstructures. The results show that a dry pressed alumina ceramic with 5 wt. % of PEG content and sintering temperature at 1200°C recorded the lowest wear rate and volume lost compared to other samples. SEM was carried out to investigate the microstructure how it affects the wear property. It was found that at high sintering temperature of 1200° C the particle formation was strengthen to each other hence promote highest wear resistance.
Development of binder system based on natural resources is one the main interest among researchers in ceramic injection moulding (CIM) with the main aim of processibility of complex biomedical implant. In this paper, the influence of single binder comprised of palm stearin mixed with HAP powder was investigated. The powder and binder mixture, generally known as feedstock was analyzed for its flowability in order to get some insight for injection moulding purposes. Two different mixing temperatures were investigated for preparing the feedstock; 160°C and 70°C. The feedstocks viscosity was then evaluated using a capillary rheometer at temperature range from 70°C to 90°C. The results clearly showed that the use of 100% palm stearin was promising in providing required pseudoplastic flow for injection molding. The injection molding process can be carried out at relatively low temperature in comparison with the conventional binder systems used.
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