钛合金表面火焰喷焊涂层中气孔的成因及增加重熔对气孔的影响

Influence of Adding Re-melting on Porosities of Spray-welding Coating on Titanium Alloys Surface and Cause of Porosities

在"一步法"火焰喷焊的基础上再增加一次重熔工艺,研究重熔对钛合金表面火焰喷焊制备的涂层中气孔的影响,并分析涂层中气孔的成因。工艺Ⅰ是在Ti6Al4V钛合金表面采用"一步法"火焰喷焊法制备镍基碳化钨涂层,工艺Ⅱ为在工艺Ⅰ制备的涂层上再增加一次重熔步骤。利用扫描电镜(SEM)对两种工艺所获取的涂层端面进行分析。扫描电镜照片显示增加一次重熔可有效地减少气孔。增加重熔后,使原来由于阴影效应和燃烧焰流大的吹力所产生的气孔和在粘稠的熔融金属上浮困难的气孔增加了气体排出机会,有效地减少了气孔;但增加重熔后,涂层中仍存在少量、小卵状的气孔,表明增加重熔可最大程度地减少气孔,但难以杜绝气孔的产生。

Adding remelting treatment on ＂one step method＂ flame spray-welding, the effects of adding re-melting treatment on flame spray-welding coating＇s porosities of titanium alloys substrate were researched. Processing I is ＂one step method＂ flame spray-welding, using this processing can spray makes Ni-based WC coating on Ti6A14V substrates. Technological II adds re-melting treatment after technological I . These coatings＇ cross section was analyzed by SEM method. Using technological I Ni-based WC coating, there are raft, vast scale and condensed porosities between titanium, alloys surface and coating. After remelting treatment, coating is better, it can effectively reduce border＇s porosities, strengthen layer＇s porosities and reduce artificial variable. After grinding external layer, there still have, appearance small ＆ ovum porosities in strengthen coating, which is decided by flame spray-welding method itself. Using flame spray-welding methods prepare coating, based on ＂one step method＂, adding re-melting treatment can reduce coating＇s porosities.