中文摘要：

以纳米WC-12Co粉末为喷涂喂料，采用超音速火焰喷涂工艺，在其它喷涂工艺参数优化的条件下，只改变枪管长度和喷涂距离，在Q235钢基体上制备了八种涂层；用X射线衍射仪和扫描电镜对喷涂粉末及涂层进行了相结构和形貌分析，探讨了枪管长度和喷涂距离对涂层显微硬度、相结构以及表面形貌的影响。结果表明：与喷距相比，枪管长度是影响纳米WC涂层显微硬度的主要因素，用长枪管制备的涂层比短枪管制备的涂层分解严重，但相应涂层的显微硬度却显著提高；当枪管长度相同时，喷距变化也会对涂层的相结构、表面形貌和显微硬度产生一定的影响。

英文摘要：

Eight kinds of nanostructured WC-12Co coatings were prepared by high velocity oxygen fuel （HVOF） spraying technology on Q235 steel substrate with different barrel lengths and spray distances. Phases of the feedstock powders and coatings were analyzed by XRD. The surface morphology of spraying powders and sprayed coatings was analyzed by SEM. The microhardness of the coatings was also tested. The results indicate that the barrel length is the key factor to control the decomposition of nanostructured WC during spraying. The coatings deposited by using long barrel experienced more severe decarburization but showed higher microhardness than those coatings deposited by using short barrel. When the barrels length was the same, spray distance also had some effect on the phases, surface morphology and microhardness of the coatings.