【作者】 王永东；

【导师】 刘瑞堂；

【作者基本信息】 哈尔滨工程大学 ， 材料学， 2009， 博士

【摘要】 在煤矿开采领域,刮板运输机中部底槽的主要材料为16Mn钢,每年因为磨损失效造成巨大的经济损失。为了提高16Mn钢的耐磨性,本文采用氩弧熔敷方法进行了Ni60A、Ti-C和Ti-C-Nb等材料体系的熔敷试验。优选出了氩弧熔敷最佳工艺参数。利用XRD、SEM、TEM等手段对涂层的微观组织进行了分析；热力学计算了原位合成TiC的可行性；研究了TiC的形成条件和长大机制,并测试了熔敷层在不同载荷作用下不同时间的摩擦磨损性能,分析了磨损机制。对不同预涂层厚度、熔敷电流、熔敷速度工艺参数下熔敷试验的硬度测试结果表明,最佳熔敷工艺参数为：预涂层厚度为1.5mm左右,熔敷电流120A,熔敷速度为8.0mm/s。微观组织和透射分析表明：熔敷层的组织分为三个区：熔敷区、稀释区和热影响区,在热影响区和稀释区交界处存在扩散层。熔敷层与基体结合无气孔、裂纹等缺陷,呈冶金结合。复合涂层内部组织存在明显的梯度分布,在表层的颗粒相比较多。对复合涂层的能谱和物相分析表明：涂层组织由γ-Ni, Cr23C6、TiC和(Ti,Nb)C颗粒相组成。TiC和(Ti,Nb)C颗粒相弥散分布在γ-Ni晶界和晶内,其形态为粒状、花瓣状、团絮状和树枝状。Nb元素固溶到TiC颗粒相中,形成(Ti,Nb)C化合物。合金粉末中Nb含量越高,(Ti,Nb)C的Nb含量就越高。TiC颗粒与基体金属的结合界面洁净,无反应物、附着物和非晶相,界面清洁。热力学分析证明氩弧熔敷条件下,熔敷过程中Ti和C发生冶金反应原位合成TiC的可行性。原位合成TiC生长基元为八面体形状,生长机制包括独立形核长大,沉淀析出和连接生长。连接生长为八面体顶角连接和棱边连接,长大形态为花瓣状、团絮状和枝晶状。通过对母材、熔敷层的磨损试验表明：在相同磨损条件下,氩弧熔敷Ti-C熔敷层的相对耐磨性是Ni60熔敷层的1.5倍,是16Mn钢的7倍；氩弧熔敷Ti-C-Nb熔敷层的相对耐磨性是Ni60熔敷层的2倍,是16Mn钢的11倍。16Mn钢的磨损机理为磨粒磨损、粘着磨损和剥层磨损；氩弧熔敷Ni60熔敷层和Ti-C复合涂层的磨损机理为磨粒磨损、粘着磨损。氩弧熔敷Ti-C-Nb熔敷层的磨损机理为显微擦划磨损和氧化磨损。原位合成TiC和(Ti,Nb)C与涂层基体结合良好,磨损过程中未发现脱落,复合涂层表现优异的抗磨性能。更多还原

【Abstract】 The central section trough of scraping belt transporter was mainly made of 16Mn steel which wear-out invalidation created huge economic loss every year in coal exploration field. In this research,cladding tests of Ni60A,TiC and Ti-C-Nb were tested by means of argon arc cladding technique to enhance wear resistance of 16Mn steel and the optimum parameters of argon arc cladding was determined. The microstructure of the coating was analyzed by XRD、SEM、TEM and the formation condition and growth mechanism of TiC were investigated. The fesibility was investigated by thermodynamic computing to which TiC is in situ synthesis,too.At the same time friction attrition resistance was tested under different load and time and attrition mechanism was analyzed.Under different thickness of pre-placed coating, welding current and cladding speed,Hardness test results indicated that the optimum parameters is the thickness of pre-placed coating with 1.5mm, the welding current with 120A and the cladding speed with 8.0mm/sMicrostructure and trasmission analysis indicated that the structure of the coating was divided into three regions,namely:the clad zone, the dilution zone and heat-affected zone and a diffusion layer was found at the interface of the heat-affected zone and the the dilution zone. Excellent bonding between the coating and the substrate is ensured by the strong metallurgical interface and the coating is uniform, continuous and almost defect-free. Interior structure of the composite coating appeard visible gradient distribution and there was more particles on the surface layer. Analysis of power spectrum and the phase indicated that the composite coating is consisted of y-Ni, Cr23C6,TiC and (Ti,Nb)C particles. The TiC and (Ti,Nb)C particles are dispersively distributed in intergranular of y-Ni. The TiC and (Ti,Nb)C particles are granular shape,the petal-like shape, flocculation-like and tree-like shape.There was (Ti,Nb)C after Nb solided into TiC particles.The more content of Nb in alloy power, the more content of Nb in (Ti,Nb)C.The interface between TiC particles and the matrix metal remained clean and free from deleterious and amorphous phase.The thermodynamic analysis indicated that in situ synthesis TiC was feasibe by the argon arc cladding. Its growth element was octahedron shape, the growth mechanism included the independent nucleation growth, the precipitation separating out and connection growth. The connection growth was in the forms of octahedron verte-linked connection and edge -shared connection and the growth form was petal-like shape, dendrite and flocculation-like shape. Wear test of the coating indicated that the relative wear resistance of Ti-C coating was 1.5 times compared with Ni60 and 7 times compared with 16Mn steel; the relative wear resistance of Ti-C-Nb coating was 2 times compared with Ni60 and was 11 times compared with 16Mn steel under same wear condition.16Mn steel wear mechanism was peeling-off type of wear, abrasion and adhesion wear; the abrasion mechanism of the Ti-C-Nb coating was micro scratch wear and the oxidation type of wear. The interface between in-situ TiC or (Ti,Nb)C and the based metal was good and no fallen off during the wear process. The composite coating had excellent wear resistance.更多还原