热处理对铝基Ni-P-纳米WC化学复合镀层组织及性能影响  

Effect of heat treatment on microstructure and properties of Al based Ni-P-nano WC composite coating

作　　者：任鑫[1] 张翀翊 赵瑞山[1] 王丞 Ren Xin, Zhang Chongyi, Zhao Ruishan, Wang Cheng(College of Materials Science and Engineering, Liaoning Technical University, Fuxin Liaoning 123000, Chin)

机构地区：[1]辽宁工程技术大学材料科学与工程学院

出　　处：《金属热处理》2018年第3期91-95,共5页Heat Treatment of Metals

摘　　要：采用化学镀技术在A356合金基体上制备了Ni-P-纳米WC化学复合镀层,并选用真空热处理的方式,对制备的Ni-P-纳米WC纳米复合镀层分别在200、300、400和500℃下进行镀后处理,与镀态下镀层性能进行对比,研究不同热处理温度对Ni-P-纳米WC复合镀层形貌、成分、物相、硬度和耐腐蚀性的影响。结果表明：试验制备的Ni-P-纳米WC复合镀层成分均匀、组织致密,镀层结构呈现非晶态;镀态下,复合镀层硬度达到917.8 HV0.1,约为基体的6倍;在3.5%NaCl溶液中的极化曲线结果显示,复合镀层自腐蚀电流密度比A356合金提高了2个数量级,起到较好的耐腐蚀效果。热处理后镀层发生晶态转变,且随热处理温度的升高,镀层晶化程度提高,400℃以上时镀层完全表现为晶态;热处理态镀层中析出Ni_3P相,镀层硬度随温度的升高呈现先升高后降低的趋势,400℃热处理镀层硬度达到1353.6 HV0.1;与镀态下相比,热处理镀层在3.5%Na Cl溶液中的耐腐蚀性下降,但是仍然表现出较好的耐腐蚀效果。Ni-P-nano WC composite coating was prepared on A356 alloy substrate by electroless plating,the Ni-P-nano WC composite coatings were subjected to vacuum heat treatment at 200 ℃,300 ℃,400 ℃ and 500 ℃,respectively. Compared with the properties of the as deposited coatings,effect of heat treatment on the morphology,component,phase,hardness and corrosion resistance of Ni-P-nano WC composite coating was studied. The results show that Ni-P-nano WC composite coating is homogeneous and compact,with amorphous structure. The hardness of the composite coating is 917. 8 HV0. 1,which is about 5 times higher than that of the substrate. In the 3. 5% Na Cl solution,the polarization curve test results show that the corrosion current density of the composite coating increases by 2 orders of magnitude compared with that of A356 alloy,which has good corrosion resistance. After heat treatment,the crystalline state of the coating changed,and with the increase of heat treatment temperature,the crystallinity of the coating increase,and the coating is completely crystalline when the temperature is above 400 ℃. The Ni3 P phase is precipitated in the heat treated coating,and the hardness of the coating increases and then decreases with the increase of temperature,the hardness of heat treated coating reaches 1353. 6 HV0. 1 under 400 ℃. Compared with the plating condition,the corrosion resistance of the heat treated coating in 3. 5% Na Cl solution decreases gradually,however,it still shows good corrosion resistance.

关 键 词：A356合金 热处理 Ni-P-纳米WC化学复合镀层 组织 性能 耐腐蚀性 

分 类 号：TG174.44[金属学及工艺—金属表面处理]