早期的研究表明, [70]提出干冰喷射作为一种简单和几乎万无一失的辅助系统来提高热喷涂涂层的质量。然而,在我们的测试中,发现干冰喷射的实施具有惊人的挑战性。通常,针对某些原料,喷枪和基材优化了热喷涂工艺。在某些情况下,这是一个微妙的平衡,尤其是颗粒和基体温度。正如本研究中所了解的,将任何类型的辅助冷却引入已经平衡的过程可能会产生意想不到的结果。 最初的实验表明,干冰喷射主要仅影响过程的温度,使其大大冷却。经过多次参数组合和逐步调整后,可能由清洁效果产生的实际效益最终得以实现。尽管空气冷却样品显得更密集,但轻度干冰喷射样品的硬度高达1482HV,而空气冷却样品的最高值为1176HV。空气冷却和干冰喷射样品的相应最低质量损失分别为179 mg和107 mg,而在磨损试验中分别为56.9 mg和50.3 mg。 似乎存在辅助干冰喷射的好处,但它们对涂层质量的积极影响并不像预期那么重要。等离子喷涂已经是一个复杂的过程,需要大量的参数进行调整,添加辅助系统会创造更多的自由度,从而使整个过程更加复杂以优化。即使在正确优化的情况下,该过程是否值得与实现的质量改进相关的额外成本也是不明确的。在喷涂参数或粉末成分调整或替代热喷涂技术不起作用的情况下,辅助系统可能会提供额外的改进途径。 随着HVOF喷枪的不断发展,氧化铬和其他陶瓷的HVOF喷涂逐渐变得更加容易和更普遍。用APS和辅助干冰喷射获得的最好的涂层仍然远远达不到HVOF喷涂氧化铬的质量水平。然而HVOF涂层工艺往往会因过热而产生质量问题,因此在HVOF涂层工艺中实施辅助干冰喷射具有很好的可能性。
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