Metal ceramic preforms were fabricated by vacuum sintering method in this work. Ti-Fe-Cr-W-Mo-V powder was used as the basic material, TiH2 and CaCO3 were used as the composite pore-forming material and Al2O3 was used as dispersal particles. The influences of fabricating parameters on infiltrating qualities and mechanical properties were discussed. The friction and wear behaviors under high temperature were investigated by pin on disk wear tester. Moreover, the microstructure and the worn surface morphology of the preforms and the composites were analyzed using scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The experimental results showed that the composite, which was sintered at 1230 oC with a holding time of 60min and was infiltrated by melt solid lubricant under a pressure of 5 MPa at 750 oC, exhibits good friction and wear behavior. The composites composed of metal ceramic hard phase and multi-lubricant soft phase with an interpenetrating network exhibit good self-lubricating properties, high obdurability and wear resistance over a range of temperature at 400-700 oC.
Abstract. A compound pore forming agent which can be decomposed constantly in sintering process was designed and prepared. A new cermet sinter was developed by adding the compound pore forming agent into the TiC/M2 matrix material. The influences of content of TiC, sintering temperature and pore forming agent content on the porosity and mechanical properties of preforms were analysed.The results show that: the sintering bodies with different properties can be prepared by changing the matrix content, sintering parameters and pore forming agent content.The preform with interpenetrating network structure can be prepared by adding 20% TiC , 6% pore forming agent, and sintering at 1220˚C for 60 minutes.
Isothermal oxidation behavior of the AISI430 stainless steel was investigated at 900°C and 950°C in air. Isothermal themogravimettric analyses were performed at high-temperature for 360ks (kilo-seconds). The microstructures of the oxide films on the stainless steel were characterized by SEM and chemical analyses were performed by EDS and X-ray diffraction. The oxide film included outer layer and inner one. The outer layer was magnetite and hematite oxides with no significant amounts of chromium and the inner one was formed by iron and chromium spinel. Significantly accelerated and anomalous oxidation was observed with the stainless steel AISI430 in air at 900°C.
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