英语翻译After an initial —usually relatively short— transient where composition varies significantlyin the clad,the process reaches a steady state.If just slight melting of the substrate occurs,thecomposition of the coating will be mostly the
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英语翻译After an initial —usually relatively short— transient where composition varies significantlyin the clad,the process reaches a steady state.If just slight melting of the substrate occurs,thecomposition of the coating will be mostly the
英语翻译
After an initial —usually relatively short— transient where composition varies significantly
in the clad,the process reaches a steady state.If just slight melting of the substrate occurs,the
composition of the coating will be mostly the nominal composition generated at the powder mixing
system.In this low dilution case,a good bond between the clad and the substrate can be obtained
without significant contamination of substrate alloy elements into the clad,which could be
detrimental to the coating performance.Moreover,significant melting of the substrate introduces a
certain amount of uncertainty in determining the coating composition.In addition to that,having a
melting powder in contact with a melting substrate could lead to the formation of regions of
intermediate compositions,e.g.intermetallic compounds,which in turn could be detrimental for
the interface mechanical behavior.This problem also arises during the previously mentioned
transient initial stage,where composition of the clad is not yet uniform.
It is readily understood that Heat Transfer plays a significant role in the whole process,
because the feasibility of a particular cladding operation depends critically on parameters such as
absorbed laser power,scanning speed (or:interaction time),and the thermal properties of the clad
and substrate,including their melting points.Therefore,modeling efforts have usually focused on
obtaining the set of adequate process parameters that lead to cladding.Nevertheless,it is important
to address also the matter of the quality of the two-layered material from the viewpoint of its
mechanical integrity.
英语翻译After an initial —usually relatively short— transient where composition varies significantlyin the clad,the process reaches a steady state.If just slight melting of the substrate occurs,thecomposition of the coating will be mostly the
镀上第一层后,工艺进入稳定状态,通常镀第一层很快,但涂料的成分各有不同,如果镀件表面只有轻微的熔化,涂层的成分不会有太大变化,在这种低稀释(咬蚀)状态下,在涂层和镀件间可获得高质量的结合力,而且双方的合金成分不会产生污染(混合),这种污染会影响涂料性能,另外,镀件表面熔化严重会对确定涂料成分产生变数,再有,熔化的涂层粉和熔化的镀件表面相接触会导致产生金属化合物,这种化合物可能对界面的机械性能(膨胀系数等)有不良影响,这种现象在初始阶段,在涂层成分不均匀的地方也会发生,热传递在整个过程中很重要,因为特定的喷涂操作的可行性要看吸收激光的能力和扫描速度(相互作用的时间)等参数,以及涂料和镀件的热传导性能,包括熔点,因此,喷涂前要获得一套完整的工艺参数,还要考虑两种材料的机械性能,这一点也很重要,