Wettability between Composing Materials and Metal for Composite Making.

复合材料与母材基体之间的润湿性是影响复合材料强度的重要因素。以前，在固滴法中，润湿性主要是通过接触角来确定的。然而，很难测量其确切值，因为铝的无根滴表面存在氧化膜，对氧有很大的亲和力。本文采用浸渍覆盖法，代替了固滴法，研究了SiC或石墨与液态铝或铝合金之间的润湿性。浸渍覆盖法将SiC或石墨片（10 mm ~ 5 mm）浸入熔融金属中，测定了SiC或石墨表面被金属润湿的面积的比例。研究发现，SiC或石墨与熔融金属的润湿过程最初有一个孕育期，在SiC浸渍过程中，通过合金化IVa、Va和VIa元素，在石墨浸渍过程中，通过合金化IVa和Va元素，孕育期缩短。润湿过程可以从润湿成核速率的角度来解释。结果表明，SiC中添加IVa、Va和VIa元素，石墨中添加IVa和Va元素，得到的总体速率常数<k_o>增大，从而改善了润湿性。SiC与Al、Al- ti、Al- v和Al- zr润湿过程的活化能在327 ~ 335 kJ/mol之间，石墨体系的活化能在365 ~ 390 kJ/mol之间。这些数值与Si-C或C-C的单键能基本一致，表明润湿过程受到SiC或石墨解离过程的限制。<k_o>和潜伏期与元素的原子序数呈周期性关系，这与铁液中碳活度系数的相互作用参数的行为类似。因此，通过合金化提高碳在铝液中的溶解度可以改善润湿性。

Wettability between composing materials and base metal matrix is an important factor for the strength of composite. Previously the wettability has been mainly determined from the contact angle in the sessile drop method. However, it is difficult to measure the exact value of , because of the presence of oxide film on the sessile drop surface of aluminium to have great affinity against oxygen. In present work, instead of the sessile drop method, the wettability between SiC or graphite and liquid aluminium or aluminium alloy was investigated by the dip coverage method where SiC or graphite disc ( 10 mm 5 mm) was dipped into molten metal and the ratio of the area wetted by metal on the SiC or graphite surface was determined. It was found that the wetting process between SiC or grahpite and molten metal had initially an incubation period that decreased by alloying IVa, Va and VIa elements in the dipping process of SiC and by IVa and Va elements in the case of grephite. The wetting process could be explained in the view-point of the nucleation rate for wetting. It was clear that the overall rate constant <k_o> obtained increased with addition of IVa, Va and VIa elements for SiC and IVa and Va elements for graphite, resulting in improvement of wettability. The activation energy for wetting process between SiC and Al, Al-Ti, Al-V and Al-Zr was obtained such as in the range from 327 to 335 kJ/mol and , for graphite system, was obtained as from 365 to 390 kJ/mol. Those values are approximately agreed with the single bonding energy of Si-C or C-C, suggesting that the wetting process is limitted by the dissociation process of SiC or graphite. The values of <k_o> and incubation period indicate a periodic relation to the atomic number of the element, which is similar to the behavior of the interaction parameter for carbon activity coefficient in liquid iron. Consequently, the wettability may be improved by increase of carbon solubility in liquid aluminium by alloying.