Papers by Keyword: Pressureless Infiltration

Abstract: In this paper, high volume fraction SiCp/Al composite was fabricated by pressureless technique with silicon carbide porous preform which fabricated through gel casting process. The effects of solid loading on the rheological properties of SiC slurry were discussed. High solid loading SiC slurry of 65vol% with low viscosity and high stability was fabricated. Also microstructure, flexural strength of the SiC preform and SiCp/Al composite were studied, the results showed gel casting process and pressureless infiltration technique were suitable for fabricating high volume fraction, homogeneous structure and high performance SiCp/Al composite.

Abstract: SiC-reinforced aluminum composite was developed by pressureless infiltration technique using polystyrene as external binder. The metal matrix composites obtained were characterized for phase composition, microstructure, density, porosity, hardness and thermal expansion. The SiC particles were uniformly distributed within the Al-Si matrix with the help of polystyrene as external binder. The variation in the density of the composites was found to be linear with volume percent of SiC. The hardness increased with increasing SiC content and highest hardness was 64.52 HV achieved with addition of 20 vol.% SiC. Thermal conductivity of the composites increased with increasing of SiC volume fraction up to 27.34 W/mK.

Abstract: The SiC network ceramics was prepared by the organic foam impregnation method and presureless sintering technologies. The network interpenetrating co-continuous SiC/Mg composites were fabricated by means of pressureless infiltration technique. The results showed that The coarse surface of the SiC network ceramics was observed in the SiC network ceramics, which was benefit for the reaction of the metal alloy during the impregnation process. The continuous and gradual interface can be found in the SiC/Mg composites. It was demonstrated that better interface structure was helpful for improving the bonding strength. Key words: Network Interpenetrating, Interface , Pressureless infiltration

Abstract: In this work, B₄C porous ceramics reinforced alumium composite was fabricated by the sponge impregnant method and pressureless infiltration technique. The wettability of aluminum on B₄C, the component and the wear resistance of the composite were studied .The result indicates that the infiltration temperature is determined 1200 centigrade and there are mainly Al, B₄C, Al₃BC , no AL₄C₃ in the experimental composite, the wear resistance of B₄C/AL composite is 25 to 30 times higher than that of the alumium.

Abstract: SiC/Al co-continuous phase composites were fabricated by pressureless infiltration technology with reticulated silicon carbide porous ceramics as matrix and aluminum or magnesium as reinforcement phase. The effect of magnesium addition and holding time on the relative density, mechanical properties and macro morphology of the composites was investigated. The results showed that the porosity of SiC/Al co-continuous phase composites decreased with the increase of the holding time. The wettability of SiC and Al was improved with the addition of Mg. The hardness of SiC/Al co-continuous phase composites increased with the increase of the holding time. SiC and Al combined closely at longer holding time.

Abstract: A new method to produce powder metallurgy (P/M) 316L stainless steel matrix composite by pressureless infiltrating Cu-10Sn alloy was studied. The effect of various compaction pressures and infiltrating temperatures on the microstructure, mechanical properties and corrosion resistance was investigated. The results show that high density P/M 316L stainless steel matrix composite could be achieved by infiltration. A maximum relative density of 98% was achieved, provided that the porosity of the skeleton was controlled at 18%~22%. After infiltration, hardness of the samples increased from 49 HRB to 89 HRB. Moreover, the critical corrosion potential reached -212 mV, close to the level of as cast 316L stainless steel. The hardness of infiltrated composite of the same density decreased with increase in initial skeleton density. It was necessary to prevent the egregious grain growth while the infiltrating temperature was too high.

Abstract: The β-SiCp/Al electronic packaging composites with excellent performance were successfully fabricated by pressureless infiltration technology in air.The effects of alloying elements, infiltration temperature and time on infiltration process and application of -SiC were studied.The results show that by adding appropriate magnesium to aluminum matrix, a interface reaction between oxide films of SiC and magnesium occurs, and the interface reaction product MgAl2O4 is generated, the interface wettability of Al and SiC and pressureless infiltration are improved.The interface harmful phase Al4C3 can be inhibited by adding silicon to aluminum matrix.Identified 850°C for the best infiltration temperature, and the thickness with infiltration time and larger, infiltration rate is about 10mm/hour.Under the same parameter conditions, the thermal properties of β-SiCp/Al electronic packaging material are 4 ~ 6% higher than that of ɑ-SiCp/Al. The β-SiCp/Al electronic packaging materials with 66% SiC volume ratio has lower coefficiency of thermal expansion than those ɑ-SiCp/Al electronic packaging materials.And the thermal expansion coefficient and thermal conductivity of β-SiCp/Al electronic material can satisfy the requirements for electronic packaging materials.

Abstract: Fe-Al2O3-TiC composite were fabricated by pressureless Ti-activated reactive melt infiltration. In this paper, a kind of Al2O3-Ti porous skeleton was prepared to be infiltrated with Fe-2Cr-3C alloy under vacuum. The microstructure and component analysis was investigated by scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). Subsequently, the wear testing was conducted to investigate the wear resistance of the Fe-Al2O3-TiC composites. The result show that the Fe-2Cr-3C alloy melt can full infiltrate the two kinds of Al2O3-Ti porous skeleton at 1390°C for 2 h. In the Fe-Al2O3-TiC composite, the coarse Al2O3 particles was surrounded by the TiC layer, which was generated by the Ti-C in-situ reaction in the infiltration process. The abrasive wear resistance of Fe-Al2O3-TiC composite is better than that of the wear resistant cast iron commonly used in industry.

Abstract: This paper adopted freeze casting method to prepare porous Al₂O₃ ceramic bodies with different volume percentage and interconnected pore channels as the preform. The porous Al₂O₃ ceramic bodies were pressureless infiltrated with Nb-35Ti-20Al-10Cr alloy (atom percentage, at%) by using electromagnetic induction furnace. The results indicated that there is a well wettability between Nb-35Ti-20Al-10Cr melt and porous Al₂O₃ ceramic body. And it would be possible to infiltrate Nb-35Ti-20Al-10Cr melt into porous Al₂O₃ ceramic body through pressureless infiltration. The microstructure observation for the Nb-35Ti-20Al-10Cr/Al₂O₃ composites demonstrated that it was still retained the layer structure characteristics of the preform. The Nb-35Ti-20Al-10Cr melt was filled into the interconnected pore channels existed in the porous Al₂O₃ ceramic bodies and the Nb, Ti, Al, Cr alloy elements diffused into the reinforced Al₂O₃ particles during pressureless infiltration.

Abstract: B₄C-CeB₆/Al composite was fabricated by pressureless infiltration technology. It is composed of the phases of Al, B₄C, AlB₂, Al₃BC and CeB₆, and Al₄C₃ is not found because of the existence of CeB₆. It could identify that AlB₂, CeB₆, and Al₃BC were formed as interfacial reaction products. Al3BC is formed on the interface of B₄C and Al; therefore it connects the aluminum with the ceramic toughly. AlB₂ as strip crystal is formed between B₄C and Al, which has higher fracture toughness.CeB6 particles in B₄C grain boundary are discovered by TEM, which caused intercrystalline rupture. Grain toughening and reinforcing, crack deflection, crack bridging is the main toughening and reinforcing mechanisms of B₄C-CeB₆/Al composites.