Effects Of Al-Si Metal Powders And Boron Bearing Additives On Properties Of Al₂O₃-SiC-C Material

Influence of complex additive on the properties, anti-oxidation and corrosion resistance of Al2O3-SiC-C material were researched in this work by adding metal powder (Al powder, crystallized Si powder and Al-Si alloy powder) and the boron bearing additives(B4C, boron glass powder). The results are listed as follows:Under oxidizing atmosphere the strength and density of Al2O3-SiC-C material are evidently improved during 600-1000 C by adding metal powders and boron bearing additive as complex additive .The modulus of rupture is the highest at 800C. The anti-oxidation is also evidently improved at mid-temperature and high temperature.Under oxidizing atmosphere boron bearing additive produces low melting B2O3 in small quantity and protect carbon network configuration, B2O3 with good flowability is produced in large quantity can form B-O-C bond at 800 C, so the strength of the material is improved. At 1000C the strength descends due to the volatilization of B2O3 and pyrex with poor flowability .At 1500C the effect of boron additives on the material is not obvious. Under reducing atmosphere the effect of boron additives on the material is not obvious.Under oxidizing atmosphere Al powder can prevent the carbon from oxidizing, protect carbon network configuration and improve the strength of the material at 600"C. The strength of the material improves with increase of the Al powder because of the formation of Al4C3, A1N and A1ON at mid-temperature and high temperature. Under reducing atmosphere works above 600 C. The strength of the material improves evidently with increase of the Al powder because of the formation of Al4C3 and A1N at mid-temperature and high temperature.Under oxidizing atmosphere crystallized Si powder can be prior to carbons and oxidize and protect the carbon structure on one hand, produce SiO2 and react with B2O3 and form pyrex on the other hand. The strength of the material improves because of needle-like Al2O3 and P-SiC. Crystallized Si powder works above 1000C under reducing atmosphere.Al powder and crystallized Si powder compounds or Al-Si alloy powder can reducing the producing temperature of Al4C3 and P-SiC, evidently improve the strength of the material at 800 C with increase of the metal powder. At 1000C the formation of SiO2 reduces viscosity of the liquid phase, the modulus of rupture descends with increase of the crystallized Si powder. The strength of the material improves evidently with increase of the crystallized Si powder because of the formation of Al4C3, -SiC, A1N and AlON at 1500C.Adding metal powder lead to high volume increase at 1500C , the sample containing Al-Si alloy powder is the highest. Remnant metal will depress the volume increase when the metal was high than 2%.Because adamantine grain was corroded by boron bearing additive the corrosion resistance depress evidently by adding crystallized Si powder and boron bearing additive as complex additive. The samples containing metal Al can depress the corrosion of the adamantine grain and had good corrosion resistance.Boron bearing additive aggravate permeate of Mg. AlON is easier than SiC to oxidize.