等离子喷涂ZrO2-NiCoCrAlY梯度涂层的 界面强化热处理工艺

在大气条件下经高温长时间保温后,ZrO     

ZrO2陶瓷热障涂层的研究

用等离子涂技术制备了ＺｒＯ２结构梯度和成份梯度涂层,并试验测定了各涂层的隔热效果及抗热震性,涂层试片在２．５Ｍａ、１８００℃、５８００ＫＷ／ｍ＾２的热流冲刷５ｓ后,结果表明：涂层表面仍较光滑,与烧蚀前无明显差别,更无剥落,崩裂出更,平均每毫米隔热涂层降温约４０２．２℃。     

等离子喷涂梯度热障涂层的抗热震性能

对比研究了等离子喷涂梯度热障涂层与双层热障涂层,试验中梯度热障涂层选用不同比例的NiCoCrAlY与ZrO₂-8%Y₂O₃复合粉末作为梯度过渡层材料,并对两种结构的热障涂层进行了抗热震性能试验。抗热震试验结果表明,梯度热障涂层的抗热震寿命明显高于双层热障涂层的抗热震寿命。     

CeO2添加剂对等离子喷涂ZrO2涂层抗热震性的影响

采用SEM,EPMA和热震方法,研究了CeO2添加剂对等离子喷涂ZrO2i涂层抗热震性能的影响。结果表明：当CeO2由0增加到9.0%（质量分数,下同）时,涂层的抗热震起裂次数和失效次数分别由32次和46次增加到76次和105次;继续增加CeO2,涂层的抗热震性能急剧下降。ZrO2 9.0?O2涂层在热循环中形成的网状微裂纹,不仅可降低涂层中的应力,也可提高涂层开裂的临界温差,从而可改善其抗热震性能。     

等离子喷涂ZrO2—NiCoCrAlY梯度热障涂层的抗热震性及失效机理

研究了ZrO2-NiCoCrAlY热障涂层的抗热震性和热震失效机理。实验结果表明,梯度热隙涂层能明显延缓热震裂纹的形成和扩展,具有较高的抗热震性。热震裂纹形成与扩展主要在粘结层与基体的界面处。随热循环次数的增加,热震裂纹可在表面陶瓷层内和陶瓷层与过渡层的界面处形成。实验表明热障涂层热震失效的过程主要是裂纹形成、扩展及涂层剥落,粘结层的氧化是导致涂层剥落失效的重要原因。     

等离子喷涂ZrO2热障涂层的抗热震性能研究

采用等离子喷涂方法在304不锈钢表面喷涂NiCoCrAIY2O3+(ZrO2+7%Y2O3)陶瓷热障涂层,模拟航空发动机涡轮叶片工作环境,研究涂层在加热和空气冷却条件下的抗热震性能.结果表明:喷涂后的涂层内部产生大量微观裂纹,随着热震次数的增加,陶瓷层内部的纵向微观裂纹通过大孔隙的连通方式逐渐在涂层内部扩展.ZrO2陶瓷喷涂后涂层主要以四方相和部分立方相组成,当涂层在热震40次时,陶瓷中的部分四方相向单斜相转变,并伴随着体积的变化,易在涂层中形成新的裂纹并加快原有裂纹的扩展.     

等离子喷涂Al2O3与ZrO2复合热障涂层的高温性能

采用等离子喷涂(PS)方法，在GH536高温合金基材上制备了传统的双层热障涂层(TBCs)和2种含有Al2O3与ZrO2陶瓷复合层的3层热障涂层。传统TBC8结构为Ni22Cr10AlY合金连接层和8％Y2O3部分稳定的ZrO2(8YPSZ)陶瓷顶层；3层TBCs中分别采用置于8YPSZ陶瓷层内层及外层的Al2O3与8YPSZ复合层。3种类型试样的100h。1050℃静态氧化试验及1050℃热震试验结果表明：3层涂层较双层涂层的氧化阻力提高，双层涂层的热震阻力最佳，氧化阻力最差。不同复合层形式试样的热振失效方式和寿命也有差别，复合层置于陶瓷层外层热震寿命略高，但100h氧化增重有明显提高，抗氧化性降低。     

微弧等离子喷涂制备莫来石/金属复合热障涂层

运用微弧等离子喷涂制备了莫来石/金属复合热障涂层.研究了涂层的微观结构、结合强度、隔热性能和抗热震性能.复合涂层结构为莫来石颗粒被"包裹"在金属层片状结构中;涂层的结合强度大于30 MPa.随着涂层中莫来石含量的增加,涂层的隔热性能有所提高,随涂层表面温度的升高,涂层的隔热温度也不断提高,涂层的最高隔热温度为125℃.1 150℃的水淬热震试验表明,基体变形是导致涂层失效的重要原因之一,随着涂层中莫来石含量的增加,涂层的抗热震次数先增加后减小,粉末中莫来石含量为40%的涂层的抗热震性能最好,抗热震次数最多为72次.     

等离子喷涂YPSZ陶瓷梯度涂层的组织与抗热震性能

利用等离子喷涂工艺在汽车铝活塞表面制备了氧化钇部分稳定的氧化锆(YPSZ)陶瓷梯度涂层,用电子扫描显微镜、金相显微镜等手段对涂层从组织形貌、物相、显微硬度和热震性能进行了分析.结果表明:基体与涂层结合紧密;涂层在冷却过程中发生了t-ZrO2→m-ZrO2的相变过程;涂层的热震性能良好,可满足活塞的使用要求.     

等离子喷涂ZrO2热障涂层热冲击破坏研究

对比研究了等离子喷涂ZrO2梯度热障涂层及传统的双层结构热障涂层,选择NiCoCrAlTaY合金粉末作为热障涂层的粘结底层材料、7％Y2O3-ZrO2作为热障涂层的面层材料、不同比例的NiCoCrAlTaY与7％Y2O3-ZrO2(YPZ)复合粉末作为梯度过渡层材料,然后进行热冲击试验、金相分析及扫描电子显微镜形貌分析,结果表明梯度热障涂层热冲击寿命明显高于传统的双层结构热障涂层。     

附加屏蔽气体的大气等离子喷涂对热障涂层性能影响

对比研究了附加屏蔽气体的大气等离子喷涂和普通大气等离子喷涂对热障涂层组织结构和性能的影响．结果表明,附加屏蔽气体的大气等离子喷涂粘结层表面未熔或半熔粒子较少,涂层中氧化物夹杂和孔隙率降低,热障涂层在1080℃下具有更好的抗氧化性能．附加屏蔽气体的大气等离子喷涂的热障涂层具有更好的抗氧化性能的原因,在于外加保护气氛减轻了...     

MICROSTRUCTURE OF NiCoCrAlY COMPONENT IN PLASMA SPRAYED ZrO_2/NiCoCrAlY GRADED COATING

ＭＩＣＲＯＳＴＲＵＣＴＵＲＥＯＦＮｉＣｏＣｒＡｌＹＣＯＭＰＯＮＥＮＴＩＮＰＬＡＳＭＡＳＰＲＡＹＥＤＺｒＯ２／ＮｉＣｏＣｒＡｌＹＧＲＡＤＥＤＣＯＡＴＩＮＧ①ＸｉａｎｇＸｉｎｇｈｕａ，ＺｈｕＪｉｎｇｃｈｕａｎ，ＹｉｎＺｈｏｎｇｄａＳｃｈｏｏｌｏｆＭａｔｅ...     

Al2O3对等离子喷涂热障涂层高温氧化及热震性能的影响

采用等离子喷涂 (PS)在GH5 36高温合金基材上制备了典型的双层热障涂层 (TBCs)和两种分别加入了Al2 O3 陶瓷成分的复合热障涂层。典型的TBCs采用Ni2 2Cr10AlY连接层与 8%Y2 O3 稳定的 (8YPSZ)顶层的双层结构 ;多层涂层分别采用Al2 O3 与Ni2 2Cr10AlY复合的连接层和Al2 O3 与 8YPSZ复合的顶层。3种类型试样的10 0h ,10 0 0℃静态氧化及 10 5 0℃热震试验的结果分析表明 :8YPSZ Al2 O3 的复合氧障层具有最佳的氧化阻力 ;Ni2 2Cr10AlY 8YPSZ双层涂层的热震阻力最佳 ,氧化阻力最差 ;连接层采用Ni2 2Cr10AlY Al2 O3 复合涂层具有热震和静态氧化条件下综合优良的高温热循环性能     

Thermal shock characteristics of plasma sprayed mullite coatings

Commercially available mullite (3Al₂O₃·2SiO₂) powders containing oxides of calcium and iron as impurities, have been made suitable for plasma spraying by using an organic binder. Stainless steel substrates covered with Ni-22Cr-10Al-1.0Y bond coat were spray coated with mullite. The 425 μm thick coatings were subjected to thermal shock cycling under burner rig conditions between 1000 and 1200 °C and less than 200 °C with holding times of 1, 5, and 30 min. While the coatings withstood as high as 1000 shock cycles without failure between 1000 and 200 °C, spallation occurred early at 120 cycles when shocked from 1200 °C. The coatings appeared to go through a process of self erosion at high temperatures resulting in loss of material. Also observed were changes attributable to melting of the silicate grains, which smooth down the surface. Oxidation of the bond coat did not appear to influence the failure. These observations were supported by detailed scanning electron microscopy and quantitative chemical composition analysis, differential thermal analysis, and surface roughness measurements.     

Plasma spraying of functionally graded yttria stabilized zirconia/NiCoCrAlY coating system using composite powders

Pre-alloyed and plasma spheroidized composite powders were used as the feedstock in the plasma spraying of functionally graded yttria stabilized zirconia (YSZ)/NiCoCrAlY coatings. The ball milling parameters of the composite powders and the plasma spraying parameters for preparing functionally graded materials (FMGs) coatings were optimized to obtain the best performance for the thermal barrier coatings (TBCs). Microstructure, physical, mechanical, and thermal properties of YSZ/NiCoCrAlY FGMs coatings were investigated and compared with those of traditional duplex coatings. Results showed that the advantages of using pre-alloyed composite powders in plasma spraying were to ensure chemical homogeneity and promote uniform density along the graded layers. Microstructure observation showed the gradient distribution of YSZ and NiCoCrAlY phases in the coating, and no clear interface was found between two adjacent different layers. Oxidation occurred during plasma spray and the resultant aluminum oxide combines with YSZ in a wide range of proportions. The bond strength of functionally graded coatings was about twice as high as that of the duplex coatings because of the significant reduction of the residual stresses in the coatings. The thermal cycling resistance of functionally graded coating was much better than that of duplex coating.     

反应等离子喷涂TiN涂层热处理后的电化学腐蚀性能

研究了热处理后TiN涂层在模拟海水中的腐蚀行为,采用电化学阻抗谱(EIS)、动电位极化曲线、扫描电镜和能谱分析等技术研究了热处理后TiN涂层电化学腐蚀参数及组织的变化。结果表明:热处理后TiN涂层的耐蚀性明显提高,自腐蚀电流仅为热处理前的13.3%,极化电阻约是热处理前的20倍;电化学阻抗谱描绘了热处理后涂层的腐蚀过程及导致涂层腐蚀的主要因素,涂层局部的孔隙腐蚀是引起电化学腐蚀参数变化的主要因素,腐蚀初期孔隙电阻由大变小,后期又会由小变大,从而使涂层的腐蚀速率发生变化;热处理会使涂层的通孔率降低为87%,主要原因是在热处理过程,TiN与大气中的O2发生了氧化反应,生成密度较TiN小的TiO2相和Ti3O相,使涂层中的部分通孔被封闭,耐蚀性得以提高。     

超音速等离子喷涂ZrO2涂层的缺陷分析与力学性能

采用超音速等离子喷涂技术(SAPS)在Q235钢基体表面制备了ZrO₂涂层。利用扫描电镜(SEM)、能谱仪(EDS)、X射线衍射仪(XRD)分别对ZrO₂涂层微观形貌、物相组成、元素分布进行了检测和分析,同时利用维氏硬度计对ZrO₂涂层硬度进行了测量,分别得出了涂层、涂层与基体连接处、基体的硬度值。结果表明:利用超音速等离子喷涂技术所制备的ZrO₂涂层表面存在大量颗粒凸起和孔洞。涂层截面存在形状为“马蹄形”、“弯月形”、“椭球形”以及“不规则多边形”的孔洞和横向裂纹缺陷,孔隙率为13%。在高温作用下,涂层中Zr元素发生扩散,由涂层顶部至底部Zr元素含量上升,且基体表面出现少量Zr元素。涂层材料在喷涂过程中发生相变,由单斜相转为四方相。涂层、涂层与基体连接处、基体显微硬度分别为740.51、205.79、189.33 HV0.2,涂层与基体连接处相比于基体材料表面的显微硬度提高。     

Thermal properties and microstructure of a plasma sprayed wollastonite coating

Wollastonite coatings were deposited using an atmospheric plasma spraying technique. The microstructure and phase compositions of the coating before and after heat treatment were investigated using scanning electron microscopy (SEM), x-ray diffraction (XRD), and differential thermal analysis (DTA) technologies, respectively. In addition, the coefficient of thermal expansion and thermal diffusivity of the coating were also investigated. Crystalline wollastonite, glassy phase, and tridymite (SiO₂) were observed in the coating. Tridymite (SiO₂) likely reacted with other composites such as CaO and glassy phase to form crystalline wollastonite when the coating was heated at about 882 °C. During the first thermal cycle, the coefficient of thermal expansion of the coating decreased dramatically between 700 and 850 °C and the thermal diffusivity of the coating was 2.7–3.1 × 10⁻³cm²/s between 20 and 1000 °C. During the second thermal cycle, the coefficient of thermal expansion of the coating increased slightly between room temperature and 1000 °C and the thermal diffusivity of the coating increased by about 20% compared with that of the first thermal cycle. The atmospheric plasma sprayed Wollastonite coating may be used as thermal barrier coating.