Papers by Keyword: Interface Reactions

Abstract: Interface reactions and wettability between melt superalloys and ceramic mould materials were investigated by using a sessile drop experiment. The wetting angle of the melt alloy on the ceramic material was calculated and the microstructure of the alloy interface was investigated by metalloscope as well as SEM. It was found that active element C in the alloy is an important factor that influences the interface reactions and the wettability. Alloys with C content lower than 0.07wt.% were almost stable on the ceramic material and no interface reaction products were found. However, alloys with C content higher than 0.16wt.% reacted with the ceramic materials. Purple reaction products were found on the alloy surface and sand adhesions were observed at the alloy-ceramic interface. In the non-reactive system, the wetting angle is in the range of 135^o-150^o. In the reactive system, the wetting angle is lower than 120^o.

Abstract: Nanometer Si powders were used as interlayer materials, which were expected to be microwave heated rapidly and reacted with the surface of Al₂O₃ ceramics to form the low eutectoid compound. The phenomena of element migration of joint samples were investigated by energy dispersive spectroscopy (EDS) and the interface phase transition was analyzed by X-ray diffraction (XRD). The results indicated that the low eutectoid compound of the joint interface wetted and penetrated to the ceramic surface. The variation of micro-hardness at the interface across the parent material was measured by micro-hardness instrument and the interfacial microstructure and the fracture surface were investigated by scanning electron microscopy (SEM).

Abstract: The thermodynamic analysis of the SiC/Al-Si-Mg system has been performed in order to find the conditions to produce SiC/Al-Si-Mg composite materials with the stable SiC/alloy interface (for both a-SiC and b-SiC) and with the solidification of primary a-Al solid solution. The conditions to avoid the formation of Al4C3 are expressed as function of temperature, and the silicon and magnesium content of the liquid aluminium alloy. It has been shown that to ensure stabilization of (the more stable) b-SiC, lower Si-content is needed and higher working temperature is allowed, compared to the requirements to stabilize (the less stable) a-SiC.