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采用电热爆炸喷涂和等离子喷涂联合制备热障涂层,以电热爆炸喷涂法在DZ125合金表面制备NiCoCrAlY粘结层,以等离子喷涂技术制备陶瓷顶层。利用扫描电镜(SEM)和X射线衍射(XRD)仪对所制备的粘结层进行分析,结果表明:电热爆炸喷涂的粘结层与基体结合良好,喷涂态的粘结层的相主要由Ni3Al组成。采用联合法制备的热障涂层,在喷涂态的陶瓷层、粘结层、基体3者结合良好,界面清晰。在高温热循环过程中,粘结层/陶瓷层界面间生成了连续、致密的Al2O3膜,阻碍粘结层的氧化。粘结层/TGO界面产生平行于界面的裂纹,是导致热障涂层失效的主要原因。 相似文献
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钟颖虹 《热处理技术与装备》2008,29(6)
采用电热爆炸喷涂法在DZ125高温合金表面制备了NiAl涂层,研究了该涂层1050℃下的循环氧化行为.利用扫描电镜(SEM)、能谱仪(EDS)和显微硬度计对热循环后的试样进行了分析.结果表明.所制备的NiAl涂层致密、晶粒细小、与基体结合良好.涂层在1050℃热循环后其表面生成了致密的Al2O3氧化层,这层Al2O3保护膜能阻止氧向内扩散,减缓内层的氧化速率,从而起到了保护基体的作用.经热循环后,基体与涂层的硬度均有所降低. 相似文献
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目的 提高热障涂层粘结层的抗高温氧化性能。方法 分别采用爆炸喷涂和等离子喷涂工艺制备了不同结构的NiCoCrAlY粘结层,之后通过等离子喷涂制备8YSZ陶瓷层,分析了两种粘结层结构的热障涂层的抗高温氧化性能。利用XRD、SEM和EDS对涂层物相、微观结构和成分进行分析,并对其与基体结合状态、抗高温氧化性能进行研究。结果 爆炸喷涂粘结层内部组织致密,缺陷较少,与基体结合处孔隙少;而等离子喷涂粘结层内部的层状特征明显,孔隙较多,表面粗糙度较低。爆炸喷涂粘结层氧化5 h后,表面生成了一层富Al2O3的致密氧化物膜;而等离子喷涂粘结层表面形成了富NiO、CoO、Cr2O3和Ni(Cr,Al)2O4的氧化物层,并出现了许多微裂纹和片层状氧化物。爆炸喷涂制备的热障涂层试样在前5 h氧化增重速率高于等离子喷涂试样,随后变平缓,而等离子喷涂试样氧化速率依然较高。爆炸喷涂热障涂层的热生长氧化物层(Thermally grown oxide, TGO)经50 h氧化后,仍呈连续状,厚度均匀,粘结层内氧化物缺陷较少。结论 爆炸喷涂粘结层组织均匀、致密,喷涂时涂层的氧化以及热处理的内氧化较少,使得足够的Al较快速地在粘结层表面形成致密的氧化铝,表面一定厚度的氧化铝层抑制了氧和其他金属原子的相向扩散反应,提高了涂层的抗高温氧化性能。 相似文献
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采用电热爆炸定向喷涂和高速电弧喷涂技术,分别制备了3Cr13不锈钢涂层.使用扫描电子显微镜(SEM)、X射线能谱仪(EDAX)、X射线衍射仪(XRD)和纳米压痕仪等分析了两种涂层的组织形貌、元素分布、相结构、纳米硬度和弹性模量等.结果表明,电热爆炸定向喷涂层比高速电弧喷涂层更致密;前者氧化现象不明显,而后者较明显;前者与基体主要是冶金结合,而后者主要为机械结合;前者的纳米硬度和弹性模量分别达到了10.3 GPa和237.8 GPa,高于后者的7.6 GPa和183.3 GPa. 相似文献
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设计了爆炸丝偏心安置实现圆管内表面电爆炸喷涂方案。通过对涂层厚度与喷涂距离之间关系的理论推导和试验研究,建立了电爆炸丝偏心安置工艺参数的计算方法。进行了圆管内表面偏心电爆炸喷涂试验,在φ57mm×120mm钢管内表面制备钼涂层。结果表明:利用偏心爆炸喷涂方法得到的涂层,在钢管轴向和周向都有较好的均匀性,电热爆炸喷涂对基体组织的影响很小。 相似文献
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J.H.Liu ) S.H.Jiang ) M.Yao ) ) Department of mechanical Engineering Engineering college Yangzhou University Yangzhou China ) Department of Material Science Yanshan University Qinhuangdao China 《金属学报(英文版)》1999,12(5):852-855
1.IntroductionFig.1 ThermalfatiguetestmachinewithOutercinstraintThedamagecausedbythermalfatigueisoneofthemainfailureformsofmetalworkingpiecesunderthetemperaturevariationconditions.Alotofthermalfatiguetestsconcerningthefailurewereconductedonthevariou… 相似文献
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A. J. Slifka B. J. Filla J. M. Phelps G. Bancke C. C. Berndt 《Journal of Thermal Spray Technology》1998,7(1):43-46
The conductivity of a thermal-barrier coating composed of atmospheric plasma sprayed 8 mass percent yttria partially stabilized
zirconia has been measured. This coating was sprayed on a substrate of 410
stainless steel. An absolute, steady-state measurement method was used to measure thermal conductivity
from 400 to 800 K. The thermal conductivity of the coating is 0.62 W/(m×K). This measurement has shown
to be temperature independent. 相似文献
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机械零件在工作温度和环境温度偏离标准设计温度后,其形状会发生改变,但由于温度场分布的不均匀性、构件材料的原子间距、内部缺陷形态等因素的影响,使得构件的热膨胀不能自由发生,导致构件热变形前后在形状上具有非相似性,理论和实验都证明这种非相似性是普遍存在的。 相似文献
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Anisotropic thermal conductivities of the plasma-sprayed ceramic coating are explicitly expressed in terms of the microstructural
parameters. The dominant features of the porous space are identified as strongly oblate (cracklike) pores that tend to be
either parallel or normal to the substrate. The scatter in pore orientations is shown to have a pronounced effect on the effective
conductivities. The established quantitative microstructure-property relations, if combined with the knowledge of the processing
parameters-resulting microstructure connections, can be utilized for controlling the conductivities in the desired way. 相似文献
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通过固相反应法合成了Gd2Zr2O7-SrZrO3 (GZSZ,Gd2Zr2O7:SrZrO3=7:3)复合陶瓷粉末,并采用喷雾造粒法和大气等离子喷涂法分别制备了适合等离子喷涂使用的相应喷涂粉末及涂层。使用X射线衍射、扫描电子显微镜对粉末和涂层的相组成、显微结构进行分析。借助激光热导仪、高温热膨胀仪对涂层的热扩散系数和热膨胀系数、烧结系数进行了表征。结果表明,制备的GZSZ复合陶瓷粉末和涂层都由Gd2Zr2O7和SrZrO3两相组成,粉末中的Gd2Zr2O7为烧绿石结构,而涂层中的Gd2Zr2O7为萤石结构,SrZrO3都为钙钛矿结构。制备态GZSZ涂层的孔隙率为~14%。GZSZ涂层1400℃热处理5 h后的热膨胀系数为(9.8~11.2)×10-6 K-1。制备态GZSZ涂层的热导率为~0.8 W·m-1·K-1,与制备态SrZrO3涂层的热导率~1.0 W·m-1·K-1相比降低~20%。1400℃热处理360 h后GZSZ涂层的热导率增加到~1.5 W·m-1.K-1。综上表明,GZSZ涂层是一种很有前景的复合陶瓷热障涂层材料。 相似文献
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S. A. Tsipas I. O. Golosnoy T. W. Clyne R. Damani 《Journal of Thermal Spray Technology》2004,13(3):370-376
Superalloy substrates coated with plasma-sprayed CoNiCrAlY bond coats and yttria-stabilized zirconia top coats (TCs) have
been subjected to a high heat flux under a controlled atmosphere. The sintering exhibited by the TC under these conditions
has been studied and compared with the behavior observed during isothermal heating. Sintering has been characterized by (a)
microstructural examinations, (b) dilatometry, in both the in-plane and through-thickness directions, and (c) stiffness measurements,
using both cantilever bending and nanoindentation. A numerical model has been used to explore the stress state under isothermal
and thermal gradient conditions. Dilatometry data indicate significant linear contractions during holding at elevated temperatures,
particularly in the through-thickness direction. This is largely attributed to microstructural changes associated with sintering,
with any volume changes due to phase transformations making relatively small contributions. Sintering proceeds faster at higher
temperatures but is retarded by the presence of tensile stresses (from differential thermal expansion between the coating
and substrate) within the TC. Thus, it occurs preferentially near the free surface of the TC under gradient conditions, not
only due to the higher temperature, but also because the in-plane stress is more compressive in that region. 相似文献
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文章针对某电缆厂的拉线机的电动机故障问题,给出一些切实可行的保护措施.对其他电动机的保护也有一定的参考价值. 相似文献