Analysis of the Liquid State Fabrication Process of High Alloy Cast Iron-Ceramic Fiber Composites

用座滴法测定了含0- 25%Cr、15%Cr-5%V和15%Cr-0.5%Ti的铸铁液在光滑透明Al_2O_3基体上的润湿角。合金熔体在熔点处的润湿角在105 ° ~ 125 °之间，且随Ti或V含量的增加而减小。较高的表面粗糙度和孔隙率降低了表面的润湿性，用Cassie方程计算了表面的表观接触角θ。采用Al-5.5%Cu合金熔体模拟了金属液在纤维预制体中的浸渗过程，由压力分布曲线得到了平均渗透率（Ka）和平均纤维半径（Rfa）。假设预型体由20个不同渗透率（K）和水力平均半径（Rh）的区域组成，模拟了预型体中的流体流动，发现随着渗透向Rh较小区域进行，压力逐渐增大。将不同合金铸铁液挤压铸造成预热的Al_2O_3短纤维预型体，在这种情况下，金属液的凝固使Rh变小，并在15%Cr-5%V铸铁中产生大量细小气孔。在Al_2O_3短纤维上初生奥氏体（γ）晶化后，根据铸铁成分，γ-VC、γ-（CrFe）_7C_3或γ-（FeCr）_3C共晶凝固，研究了含8vol.%左右的Fe-2.7%C-1.5%Cr-1%Mo-0.4%Si-0.8%Mn铸铁的耐磨性在Suga磨损试验机上对Al_2O_3短纤维进行了磨损试验，结果表明，添加Al_2O_3短纤维的铸铁的磨损率仅为相同化学成分的无纤维铸铁的1/2。

The wetting angles of molten cast irons containing 0-25%Cr,15%Cr-5%V or 15%Cr-0.5%Ti were measured on smooth transparent Al_2O_3 substrates by the sessile drop method. The wetting angles of these molten alloys were among 105ﾟand 125ﾟat the melting points,and they decreased with the increase in Ti or V content. The higher surface roughness and porosity of substrates decreased the wettability.The apparent contact angles(theta)of these substrates were evaluated by Cassie's equation. Further,the wettability and the interface reaction of the above cast iron melts on sintered ZrO_2,SIA LON,Si_3N_4,SiC and WC were also clarified.The infiltration process of molten metal into fibrous perform,heated to the same temperature as the molten metal,was simulated by using Al-5.5%Cu alloy melt.The average permeability(Ka)and the average fiber radius(Rfa)were obtained experimentally from the pressure profile. The perform was assumed to be composed of 20 different permeability(K)and hydraulic mean radius(Rh)regions,and the simulation of fluid flow in the perform revealed that the pressure gradually increased as the infiltration proceeded to smaller Rh regions.The squeeze casting of various molten alloy cast irons into pre-heated Al_2O_3 short fiber perform was conducted.In this case,the solidification of molten metal made the Rh smaller,and caused many small pores especially in 15%Cr-5%V cast iron.The solidification processes of these alloys were as follows. After the crystallization of primary austenite(gamma) on Al_2O_3 short fibers,gamma-VC,gamma-(CrFe)_7C_3, or gamma-(FeCr)_3C eutectic solidified according to the composition of cast iron.The abrasion wear registance of Fe-2.7%C-1.5%Cr-1%Mo-0.4%Si-0.8%Mn cast iron with about 8vol.%Al_2O_3 short fibers was investigated by Suga-type wear testing machine.The wear rate of the cast iron with Al_2O_3 fibers decreased under 1/2 of that of the fiber-free cast iron of the same chemical composition.