Papers by Keyword: Vacuum Condition

Abstract: Metal Injection Moulding (MIM) is an efficient method for high volume production of complex shape components from powders. The purpose of this study is to determine the sintering condition of titanium alloy (Ti6Al4V) tensile shape sample. In high temperature, Ti6Al4V will react with oxygen to form of titanium oxide (TiO₂) which present a problem during sintering thus affected the mechanical properties and microstructure. This reaction can be avoided either by introducing argon gases or in vacuum condition. Ti6Al4V with binder formulation consist of polyethylene (PE), paraffin wax (PW), stearic acid (SA) and palm oil derivatives; palm stearin (PS) were mixed homogenously and injected to produce green compact. The binders then are removed and sintered at 1100 °C for 8 h. During sintering, the debound part is heated, thus allowing densification of the powder into a dense solid with the elimination of pores. It was expected that the impurity gas in argon had strong effects on aspects of the densification and properties. Samples of PE/PS formulation with argon added to the sintering atmosphere, experience density of 4.375g/cm₃ and tensile strength stated at 1000.100MPa compared to samples in vacuum condition which do not show any significant increment with density of 3.943g/cm₃ and tensile strength at 325.976MPa. PE/PW/SA samples of vacuum condition also show no improvement in sintered properties. However with additional argon flow the density can reach until 4.359g /cm₃ and 940.823MPa of tensile strength. Ti-alloy sintered in argon exhibited better densification rate than in vacuum with high strength, better elongation and lower porosity. In argon, the powder particles became interconnected signifying densification was achieved due of non-reactive properties of inert gases that prevent undesirable chemical reactions from taking place.

Abstract: The microwave desorption azeotropic distillation was used to recover ethanol in waste water from ethanol industry under vacuum condition. The flow charts for microwave desorption azeotropic distillation of ethanol-loaded activated carbon under vacuum condition were designed. Activated carbon is used in adsorption of low concentration ethanol in water, and the saturated carbon is regenerated by microwave irradiation under vacuum condition. The results showed that the ethanol-loaded activated carbon can be desorbed nearly completely after 100s; the microwave power has an important effect on the outlet concentration curve of ethanol; the mass defect of the regenerated carbon is lower than 5%. After several processes of activated carbon adsorption and microwave desorption azeotropic distillation under vacuum condition, the concentration of ethanol can come up to 98%.

Abstract: The friction and wear behavior of Si₃N₄, SiC and ZrO₂ sliding against M50 bearing steel under vacuum condition at various applied load were investigated. The results showed that the properties of different ceramic materials cause the difference in wear behaviors. The coefficient of friction was lowest in SiC and M50 bearing steel couple than other cases for graphitic carbon replaced carbidic carbon at the worn layer of SiC. The specific wear rate of ZrO₂ was highest and the lowest was Si₃N₄. The ceramic ball materials have transferred on M50 bearing steel surfaces and tribofilm consistently formed on the ceramic balls wearing surfaces. Dominant wear behaviors for three structural ceramics were adhesion abrasion, plastic deformation and brittle fracture. The couple with Si₃N₄ and M50 showed the best operating conditions for friction and wear resistance under higher applied load.

Abstract: Sliding wear was investigated for ZrO2 ceramics against M50 bearing steel under vacuum condition. The research was studied on the ball-disk machine under different loads and steady sliding velocity. The worn surfaces of tested samples were examined using optical microscope, scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy. The results showed that the friction coefficient of ZrO2 was decided by the applied load, the critical load of ZrO2 was 10N applied load under vacuum condition, the specific wear rate of ZrO2 drop rapidly with exceeded applied critical loads. The ZrO2 ceramics materials have transferred on the M50 bearing steel surface under high vacuum condition. The dominant wear mechanisms of ZrO2 ceramics were mico-adhesion, tribochemical wear, brittle scraps and micro-furrow wear under vacuum condition.

Abstract: The friction and wear performances of Si3N4 ceramics sliding against bearing steel and to find optimal operating condition against M50 bearing steel couples under high vacuum surroundings were investigated. The tests were studied on the ball-disk machine under different loads and steady sliding velocity. The worn surfaces of tested samples were examined using optical microscope，SEM and XPS. The results showed that the friction coefficient of Si3N4 was decided by the applied load, the critical load of Si3N4’ friction coefficient was 10N applied load; The critical load of Si3N4’ specific wear rate was 5N applied load, the specific wear rate of Si3N4 drop rapidly as the applied load exceeded the critical load; The dominant wear mechanisms of Si3N4 ceramics were adhesion wear, brittle facture and furrow wear in vacuum.