B清除大气等离子喷涂CuNi熔滴氧化物效应  

Oxide Cleaning Effect of In-Flight CuNi Droplet During Atmospheric Plasma Spraying by B Addition

作　　者：任媛 董昕远 孙浩 雒晓涛[1] 李成新[1] M.Mahrukh 李长久[1] REN Yuan;DONG Xinyuan;SUN Hao;LUO Xiaotao;LI Chengxin;M.Mahrukh;LI Chang-Jiu(State Key Laboratory for Mechanical Behavior of Materials,Xi􀆳an Jiaotong University,Xi􀆳an 710049,China)

机构地区：[1]西安交通大学,金属材料强度国家重点实验室,西安710049

出　　处：《金属学报》2022年第2期206-214,共9页Acta Metallurgica Sinica

基　　金：国家自然科学基金重点项目Nos.52031010和U1837201。

摘　　要：提出了粉末中添加B的成分设计,实现通过B牺牲氧化而保护合金元素不氧化从而发展高温CuNi熔滴自清洁氧化物效应。采用CuNi2B与CuNi4B 2种粉末,通过大气等离子喷涂工艺制备涂层,通过SEM、EDS、XRD和ICP-OES等方法研究了B含量与喷涂距离对CuNi涂层组织结构与性能的影响。结果表明,熔滴可加热至1900℃以上,粉末中B的引入可抑制飞行中高温熔滴中的合金元素的氧化,从而显著降低CuNi涂层中的O含量,而该效果受熔滴中B含量影响显著。采用4%B的CuNi合金粉末时,随着喷涂距离的增加,涂层中的氧化物显著降低,涂层中的O主要由熔滴沉积后的氧化引入,优化喷涂工艺制备的涂层O含量降低至0.43%,显著低于CuNiIn涂层的3.5%。当CuNi粉末含B为1.83%时,在距离超过100 mm,B含量降至0.5%以下时,不足以抑制等离子喷涂过程中飞行颗粒的合金元素氧化,故实现高温熔滴氧化保护的临界B含量约为0.5%。研究发现,B添加可引起合金熔点降低效应与去氧化物净化效应,从而显著增强了CuNi粒子间的冶金结合,提高了涂层的致密性;涂层B含量随粉末成分与工艺参数从0.26%增加至3.61%,而CuNi涂层硬度则随B含量增加从151 HV_(0.2)线性增加至457 HV_(0.2)。A large amount of air is drawn into the high-temperature plasma jet during the atmospheric plasma spraying(APS)process because it operates in an atmospheric environment,thus oxidizing metalspray particles.The oxide inclusion resulting from in-flight droplet oxidation inhibits the metallurgical bonding between lamellae in the coating,which limits the applications of plasma-sprayed metal coatings.In this study,a novel approach to create oxide-free molten droplets is proposed by adding B to the CuNi powder to achieve sacrificial oxidation of B in the high-temperature droplet and protect the alloy elements from oxidation.Two powders of CuNi2B and CuNi4B were prepared to deposit the coatings via APS.The effect of B content and spray distance on the microstructure,as well as the O content of CuNi coating,was studied using methods such as SEM,EDS,XRD,and inductively coupled plasma-optical emission spectrum(ICP-CES).The results show that the droplet can be heated to more than 1900℃,and the introduction of B in the powder can inhibit the oxidation of alloy elements in the high-temperature droplet during flight,thus reducing the oxygen in the CuNi coating.Moreover,the deoxidizing effect is affected by the B content of the droplet.Using 4%B CuNi alloy powder and increasing spray distance,the oxide in the coating is reduced.The oxygen in the coating is introduced via oxidation after droplet deposition,and the oxygen content of the coating prepared using the optimized spraying process is reduced to 0.43%,which is considerably lower than 3.5%of CuNiIn coating.An increase in the spray distance and a reduction in B content of CuNi powder,which contains 1.83%B,to 0.5%is insufficient to inhibit the oxidation of the alloying elements of the in-flight particles.The result yields a critical B content of approximately 0.5%for high-temperature droplet oxidation protection.The increase in the B content decreases the melting point,as well as the oxidation of the alloy,thus enhancing the metallurgical bonding between CuNi particles and

关 键 词：CuNiIn涂层 CuNiB涂层 组织与性能 层间结合 自熔效应 等离子喷涂 

分 类 号：TG174.4[金属学及工艺—金属表面处理]