石墨对激光熔覆铁基非晶复合涂层组织和性能的影响

Effects of Graphite on Structure and Property of Laser Cladded Fe-Based Amorphous Composite Coatings

在304L不锈钢表面,利用激光熔覆技术制备了添加石墨的Fe基非晶复合涂层,并研究了石墨的添加对涂层组织和性能的影响。结果表明,未添加石墨的涂层主要由α-Fe、含硼相(Fe_(23)B_6、CrB)和γ-(Ni,Cr,Fe)物相组成,非晶相体积分数为35.9%;而加入石墨的涂层新生成了含碳相(Fe_3C、Cr_7C_3),且涂层中的非晶体积分数增加至41.6%。未添加石墨的涂层结合区弥散分布着不规则颗粒相,熔覆层形貌呈稻穗状;添加石墨后的涂层结合区组织呈胞状树枝晶形貌,熔覆层形貌则为分布有深灰色近球状颗粒的针状组织。添加石墨前后的试样熔覆层平均显微硬度值分别为792.2HV和968.7HV。

Fe-based amorphous composite coatings added with graphite are fabricated on 304L stainless steel surface by laser cladding with the addition of graphite. The effects of the added graphite on the microstructure and property of these coatings are studied. The results show that the coatings without graphite addition are composed of α-Fe, boron-containing phases （Fe23 B6 , CrB） and 7-（Ni, Cr, Fe） phases, and the volume fraction of the amorphous phase is 35.9%. However, in those with graphite addition, the new carbon-containing phases （Fe3C and Cr7C3） are formed, and the volume fraction of the amorphous phase is increased to 41.6%. The bond zones of coatings without graphite addition are evenly distributed by irregular granular phases and the cladding layers have a rice-like shape. The bond zones of coatings with graphite addition exhibit cellular dendrites, and the cladding layers have a needle- like crystal structure where dark gray spherical particles are embedded. The average microhardness of the cladding layers before or after graphite addition is 792.2 HV and 968.7 HV, respectively.