电子束作用下氧化锆热障涂层传热数值模拟与实验

发布时间：2018-06-08 14:41

本文选题：大气等离子体喷涂 + 氧化锆热障涂层　；参考：《深圳大学》2017年硕士论文

【摘要】：大气等离子体喷涂制备氧化锆热障涂层是目前主流的生产工艺,它具有生产效率高、制备的涂层质量好、成本较低等优点,同时涂层存在孔隙率高、致密度低和服役时间短等缺陷。服役过程中孔隙的存在致使高温热流或其他腐蚀介质通过孔隙对金属材料造成腐蚀,导致涂层隔热失效,甚至造成涂层脱落。本文通过建立氧化锆涂层传热模型,对大气压等离子体制备的氧化锆热障涂层电子束重熔过程中传热进行数值模拟并开展重熔实验,实现对涂层的封孔处理。研究初步结果表明:氧化锆涂层在电子束作用下,涂层的温度分布及重熔深度取决于电子束功率密度、作用时间。当功率密度分别在0.8-1.4 GW/m~2、9-10.5MW/m~2间变化时,相应的作用时间为200μs、100ms,计算表明,涂层表面温度随着功率密度的增加而增加,涂层表面50μm厚度纵向最大温度梯度分别为:2.0×10~5K/cm和1.9×10~5K/cm,最大重熔深度为80μm和83μm。当功率密度分别为1.4GW/m~2、10.5MW/m~2时,相应作用时间在50-200μs、30-100ms区间变化时,涂层表面温度随着时间的增加而增加。对不同喷涂功率制备的氧化钇稳定氧化锆热障涂层(YSZ涂层)进行主要性能表征和测试,获取最佳工艺参数制备涂层。制备的YSZ涂层分别在强流脉冲电子束(3.8GW/m~2、脉冲时间200μs、脉冲次数50)、扫描电子束(25 MW/m~2、100ms)作用下进行重熔封孔处理并表征。实验表明:重熔后涂层孔隙几乎完全封闭,孔隙率比重熔前降低了50-80%,最低只有2.59%;X射线衍射分析表明,氧化锆热障涂层在电子束高温作用下发生脱氧和氮化,生成了黑色的Zr_2ON_2;表面显微硬度提升了26%-57%;通过吹砂实验测试,经电子束重熔后的涂层耐冲刷能力提升了33%-560%。重熔处理后氧化锆涂层的性能有了显著的提升。
[Abstract]:The thermal barrier coating of zirconia prepared by atmospheric plasma spraying is the mainstream production technology at present. It has the advantages of high production efficiency, good quality and low cost, and the porosity of the coating is high. Low density and short service time. The existence of pores during service results in the corrosion of metallic materials by high temperature heat flux or other corrosive media through pores, which results in the failure of thermal insulation and even the exfoliation of coatings. In this paper, a heat transfer model of zirconia coating is established to simulate the heat transfer during electron beam remelting of zirconia thermal barrier coating prepared by atmospheric pressure plasma. The preliminary results show that the temperature distribution and remelting depth of zirconia coating depend on the electron beam power density and the action time. When the power density varies between 0.8-1.4 GW / m ~ 2 ~ 10.5MW / m ~ 2, the corresponding time is 200 渭 s / m ~ (-1). The calculation shows that the surface temperature of the coating increases with the increase of the power density. The longitudinal maximum temperature gradient of 50 渭 m thickness on the surface of the coating is 1: 2.0 脳 10 ~ (5) K / cm and 1.9 脳 10 ~ (5) K / cm, respectively. The maximum remelting depth is 80 渭 m and 83 渭 m, respectively. When the power density is 1.4 GW / m ~ 2 and 10.5 MW / m ~ 2 respectively, the surface temperature of the coating increases with the increase of time when the corresponding time varies in the range of 50-200 渭 s / m ~ (-1) Ms. The main properties of yttrium stabilized zirconia thermal barrier coating prepared by different spraying power were characterized and tested. The optimum process parameters were obtained to prepare the coating. The YSZ coatings were remelted and characterized under the action of high current pulsed electron beam 3.8GW / m-2, pulse time 200 渭 s, pulse number 50 渭 s, and scanning electron beam 25MW / m ~ 2100ms). The experimental results show that the pores of the coating are almost completely closed after remelting, the porosity of the coating is reduced by 50-80 than that before remelting, and the lowest is 2.59and X-ray diffraction analysis shows that the zirconia thermal barrier coating is deoxidized and nitrided under the action of electron beam at high temperature. A black Zr2ON _ 2 was formed; the surface microhardness was increased by 26-57; and the erosion resistance of the coating after electron beam remelting was increased by 33-560 through the sand blowing experiment. The properties of zirconia coating after remelting treatment were improved significantly.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：V231;O539

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