Properties of plasma sprayed NiCrAlY (ZrO_2 Y_2O_3) coating on refractory steel surface

1INTRODUCTION1Cr18Ni9Ti,i.e.188austeniticstainless steel,isakindofausteniticrefractorysteelwidely appliedinmanyfields,containingahighcontentofCrthatcanimproveheatandoxidationresistances,andalsoNicapableofformingastableaustenitic structure.However,suchstee…     

Corrosion resistance of plasma sprayed NiCrAl+(ZrO2+Y2O3) thermal barrier coating on 18-8 steel surface

The corrosion resistance of NiCrAl+(ZrO₂+Y₂O₃) thermal barrier coating, formed with the plasma spraying technique, on the 18 - 8 steel surface was investigated. The phase structure and morphology of the coating were analyzed by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical corrosion behavior of the coating in 1.0 mol/L H₂SO₄ solution was studied by using electrochemical measurement methods. The results show that the gradient plasma spraying coating is composed of the NiCrAlY coating and the (ZrO₂+Y₂O₃) top coating, and the coating thickness is 360 μm. The microhardness of coating reaches 1 100 HV. The corrosion resistance of the plasma sprayed coating of the 18 - 8 steel surface is about 5 times as great as that of the original pattern. The corrosion resistance of the coating is enhanced notably. Foundation item: Project (5040202140) supported by Scientific Research Common Program of Beijing Municipal Commission of Education     

Effect of ZrO2 （9mol % Y2O3） coating thickness on the electronic conductivity of Mg-PSZ oxygen sensors

The ZrO2 (9mol% Y2O3) coating was prepared evenly on the surface of MgO partially stabilized zirconia (Mg-PSZ) tube (oxygen sensor probe) by dipping the green Mg-PSZ tube in a ZrO2, (9mol% Y2O3) slurry and then co-firing at 1750℃ for 8 h. The double-cell method was employed to measure the electronic conductivity parameter and exam the reproducibility of the coated Mg-PSZ tube. The experimental results indicate that the good thermal shock resistance of the Mg-PSZ tube can be retained when the coating thickness is not more than 3.4μm. The ZrO2 (9mol% Y2O3) coating reduces the electronic conductivity parameter remarkably. probably due to the lower electronic conductivity of Y2O3-stabilized ZrO2 than that of MgO-stabilized ZrO2. Moreover, the ZrO2(9mol% Y2O3) coating can improve the reproducibility and accuracy of the Mg-PSZ tube significantly in the low oxygen measurement. The smooth surface feature and lower electronic conductivity of the coated Mg-PSZ tube should be responsible for this improvement.     

Investigation on plasma-sprayed ZrO_2 thermal barrier coating on nickel alloy substrate

1　ＩＮＴＲＯＤＵＣＴＩＯＮＺｒＯ2 ｔｈｅｒｍａｌｂａｒｒｉｅｒｃｏａｔｉｎｇｓａｒｅｍａｉｎｌｙｕｓｅｄａｓｈｅａｔ ｉｎｓｕｌａｔｉｎｇｌａｙｅｒｏｎｔｈｅｓｕｒｆａｃｅｏｆｈｉｇｈｔｅｍ ｐｅｒａｔｕｒｅｃｏｍｐｏｎｅｎｔｓｉｎｔｈｅｆｉｅｌｄｏｆｄｉｅｓｅｌ,ｔｕｒ ｂｉｎｅ ,ａｎｄｊｅｔｅｎｇｉｎｅｓ.Ｔｈｅｓｕｒｆａｃｅｔｅｍｐｅｒａｔｕｒｅｏｆｔｈｅｈｏｔｃｏｍｐｏｎｅｎｔｓｃａｎｇｒｅａｔｌｙｂｅｒｅｄｕｃｅｄｕｓｉｎｇｔｈｅｈｅａｔ ｉｎｓｕｌａｔｉｎｇｌａｙｅｒ,ｗｈｉｃｈｒｅｓｕｌ…     

AZ91D镁合金表面等离子喷涂Al_2O_3-TiO_2陶瓷涂层的微观组织及防护性能

采用大气等离子喷涂技术在AZ91D镁合金表面制备Al2O3-TiO2陶瓷涂层。对涂层的显微组织、化学成分、相组成及显微硬度进行表征,并对涂层的耐磨损和耐电化学腐蚀防护性能进行研究。结果表明,Al2O3-TiO2陶瓷涂层的组织呈现层状结构,主要组成相为α-Al2O3、γ-Al2O3和金红石TiO2。涂层平均硬度654.2HV,涂层具有良好的抗磨损和抗电化学腐蚀防护性能。     

铝合金上等离子喷涂NiCrAlCoY/ZrO2梯度热障层连接的研究

利用等离子喷涂法在发动机铝合金活塞上制得NiCrAlCoY与用质量分数为8％的Y2O3稳定的ZrO2梯度热障层。经热震实验、金相分析、SEM分析和TEM分析，结果表明该热障层具有良好的抗热冲击性和高温热稳定性，并且NiCrAlCoY与ZrO2间形成了化学键结合。这为今后解决TBCs可靠性的问题提出了新的思路。     

爆炸喷涂Al2O3陶瓷涂层的摩擦磨损性能

爆炸喷涂是提高材料表面性能的表面喷涂技术之一.本文旨在通过表面喷涂提高45钢基体表面的耐磨性、耐冲击性等性能.采用爆炸喷涂方法在45钢基体材料上喷涂Al2O3陶瓷和团聚陶瓷涂层,在摩擦磨损试验机上进行Al2O3陶瓷涂层的磨损试验,X衍射仪测试涂层表面结构,JB/T7509—94铁试剂方法测试涂层的孔隙率.通过分析和比较45钢基材与爆炸喷涂Al2O3陶瓷涂层的摩擦磨损性能,实验结果表明,喷涂Al2O3陶瓷涂层可以改善基材45钢的耐磨损性能,延长其使用寿命.此外,研究发现,团聚Al2O3陶瓷涂层比Al2O3陶瓷涂层要更耐磨;而爆炸喷涂Al2O3涂层的质量要好于等离子喷涂和火焰喷涂Al2O3陶瓷涂层.     

镁合金表面等离子喷涂纳米陶瓷涂层研究

为了扩大镁及其合金的应用范围，必须有效地提高其表面的硬度、耐磨性、耐腐蚀性和瞬时耐热性。在压铸镁合金的表面用具有纳米尺寸的Al2O3 3％TiO2粉粒进行等离子喷涂，并借助XRD、AFM、SEM等分析方法，对涂层的微观组织进行了观察分析，并对涂层和基体的结合强度及表面硬度进行了测量。     

CoNiCrAlTaSiY涂层抗热腐蚀性能

用大气等离子喷涂方法在基体材料ＧＨ８６４（Ｗａｓｐａｌｏｙ）合金上制备ＣｏＮｉＣｒＡｌＴａＳｉＹ涂层，在７５０℃／１００ｈ的熔盐热腐蚀试验，测定该涂层的抗热腐蚀性能．用ＳＥＭ、ＳＴＥＭ、ＸＲＤ，ＥＭＰＡ等观察涂层形貌、成分及组织结构变化，并讨论抗热腐蚀机理。结果表明，ＣｏＮｉＣｒＡｌＴａＳｉＹ涂层的热腐蚀性能取决于Ｓ（２－）通过缺陷进入涂层内形成腐蚀产物和涂层表面防护性氧化层的形成。该涂层具有较好的抗热腐蚀性能。提出了ＣｏＮｉＣｒＡｌＴａＳｉＹ涂层抗热腐蚀过程模型，阐明了抗热腐蚀机理。     

热喷涂铝涂层在矿井水中的耐蚀性能研究

应用腐蚀失重方法和电化学极化技术研究了热喷涂铝涂层在矿井水环境下的耐腐蚀性能,并与普通碳钢Ｑ２３５进行对比．实验结果表明,在一般中性矿井水中,涂层的自腐蚀电位附近的腐蚀受阴极氧扩散控制,当电位较高时,阳极上有氢析出,阳极反应由此变得复杂;用阴极极化能更好地显示涂层的电化学极化过程．热喷涂铝层具有较高的耐蚀性,实验涂层的预计使用寿命为２０ａ．比较了用失重法和电化学法计算涂层腐蚀速度的结果;分析了在２０～６０℃范围内温度对涂层腐蚀过程的影响     

溶胶凝胶旋涂法制备不锈钢Al2O3-CeO2-Y2O3复合涂层

本文以Al（NO3）3·9H2O,Ce（NO3）3·6H2——Y（NO3）3·6H2O为原料,PVP（聚乙烯吡咯烷酮）为稳定剂,用sol-gel法通过共沉淀水解再胶溶的办法,得到透明、稳定性能好的复合溶胶.利用旋涂法在SUS304不锈钢基体表面涂覆凝胶膜,经热处理得到复合涂层.采用XRD、SEM、EDS和电化学工作站等测试技术对复合涂层的相组成、微观形貌、成分及耐腐蚀性能等进行测试、表征.实验结果表明：用溶胶凝胶旋涂法能够成功制备出均匀的Al2O3-CeO2-Y2O3复合涂层.当主盐硝酸铝的浓度为0.60 mol/L,加入PVP含量为0.3 mol/L时,旋涂速度为3000r/min,旋涂8次,采用自然干燥再经过800℃煅烧能制得较为均匀连续,并且具有优良抗腐蚀性能的Al2O3-CeO2-Y2O3复合涂层.     

激光重熔热障涂层热震行为研究

在GH635高温合金基材上等离子喷涂NiCrAlY/85Y2O3-ZrO2热障涂层，进行激光重熔，对不同激光工艺参数下的试样进行表面形貌观察并进行热震试验，试验结果表明：采用4.0J/mm^2的激光能量密度可以得到较好的表面质量，并且具有高于等离子喷涂试样的热震寿命。     

Properties of plasma sprayed NiCrAlY+(ZrO2+Y2O3) coating on refractory steel surface

NiCrAlY+(ZrO₂+Y₂O₃) thermal barrier coating was prepared on the surface of refractory steel 1Cr18Ni9Ti with plasma spraying technique. The phases and microstructure of the thermal barrier coating were determined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the bonding between thermal barrier coating and substrate is sound. The surface hardness of 1Cr18Ni9Ti reaches up to 1 000 HV, but that of substrate is only 300 HV. The patterns sprayed with CoNiCrAlY+(ZrO₂+Y₂O₃) ceramic coating have a good heat insulation effect at 800 °C for heat insulation temperature difference reaches 54 °C, which increases the operating temperature and service life of refractory steel. Foundation item: Project (5040202140) supported by Scientific Research Common Program of Beijing Municipal Commission of Education     

Ni-P/Al_2O_3复合镀层性能的表征与测试

为了提高镀层的耐磨性和硬度,在45碳钢基材上实施Ni-P/Al2O3化学复合镀,使纳米Al2O3微粒均匀分布于Ni-P基体中.研究了化学复合镀工艺条件和镀液组分对镀层性能的影响.镀件的耐蚀性实验和XRD分析表明:当硫酸镍25 g/L,次亚磷酸钠30 g/L,纳米Al2O3微粒加入量为5 g/L,乳酸20 mL/L和柠檬酸5 g/L,在pH=5.5,施镀温度为(85±2)℃,获得的Ni-P/Al2O3复合镀层表面光滑、胞状物致密,镀层的耐腐蚀性较高、硬度可达600HV,有利于得到综合性能较高的镀层.     

镁合金AM60表面改性及其在Hank's溶液中的腐蚀

采用等离子喷涂TiO2对镁合金AM60进行表面改性,利用扫描电子显微镜和能谱发现分别观察了涂层结构,分析了其化学成分,通过表面纳米划痕实验研究了涂层的力学性能,用动电位电化学方法测量镁合金及其涂层的腐蚀性能.研究表明:AM60镁合金表面等离子热喷涂TiO2涂层具有多孔的陶瓷结构,存在鳞片状和菜花状/珊瑚状2种形貌,涂层鳞片状部位氧含量要高于菜花状部位的氧含量,涂层的显微硬度的平均值为886 HV,划痕实验表明涂层与基体结合良好,封闭后的涂层明显地提高了镁合金在Hank's溶液中的耐蚀性能.     

激光熔覆Ni+Cr_2O_3复合涂层的耐蚀性

研究了激光搭接熔覆Ni+Cr2 O3复合涂层在 0 .5mol/LH2 SO4 +0 .5mol/LNaCl水溶液中的电化学行为 .试验表明Cr2 O3粒子在激光熔池中发生了完全溶解 ,涂层具有胞状枝晶组织特征 .激光熔覆Ni+Cr2 O3复合涂层比单一熔覆Ni合金涂层和 2Cr13马氏体不锈钢基材具有更低的维钝电流密度和更宽的钝化区范围 ,明显改善了在该腐蚀介质中的抗点蚀能力 .     

冲蚀条件下等离子喷涂Al2O3陶瓷涂层的磨损特性

研究了在固体颗粒冲蚀条件下 ,不同冲击速度、不同磨料尺寸等因素对等离子喷涂Al2 O3 陶瓷涂层冲蚀磨损率的影响 ,并在不同条件下与 2 0钢进行了对比试验 ,分析了等离子喷涂Al2 O3 陶瓷涂层的冲蚀磨损特性及磨损机理 ,提出等离子喷涂Al2 O3 陶瓷涂层具有脆性特征的冲蚀磨损特性 ,它适用于细磨料低速冲蚀磨损条件     

Influence of oxides on high velocity arc sprayed Fe-Al/Cr_3C_2 composite coatings

1INTRODUCTION Arcspraying(AS)isatechniquethatthemet alisheatedtodropletsbyanelectricarcandthensprayedontosubstratesbythecompressedair. Highvelocityarcspraying(HVAS)technologyisdevelopedonthebasisofAS.Aspecialtubede signedaccordingtotheprincipleofaerodynamicsis mountedattheexitofcompressedair.Theveloci tyanddistributionofmelteddropletsbecomehigh erandmoreuniform,respectively.Asaresult,acoatingwithlowporosity(2%)andhighdensity andbondstrengthcanbeobtained[15].Fe Alin termetalliccompound…     

New pattern Zn-Al-Mg-RE coating technics for steel structure sustainable design

Based on the advanced integrated technology of materials preparation and formation, a new pattern ZnAl-Mg-RE anti-corrosion coating for steel structure sustainable design was manufactured by cored wires and high velocity arc spraying (HVAS) technologies. The developments of thermally sprayed coatings for steel structure protection were described. Based on Al, Zn, Zn-Al and Zn-Al-Mg coatings, the anti-corrosion properties of new-pattern Zn-Al-Mg-RE coating were evaluated through electrochemical methods including electrochemical polarization and electrochemical impedance spectroscopy (EIS) coupled with SEM and XRD. The models of Zn-Al-Mg-RE coating undergoing corrosion with the initial pinhole defect and the latter with accelerated products were also discussed. The results show that Zn-Al-Mg-RE coating exhibites excellent corrosion resistance for long-term immersion, which is helpful for the sustainable design of steel structure in aggressive corrosion conditions. And the corrosion products seem to possess certain self-sealing function.     

New pattern Zn-Al-Mg-RE coating technics for steel structure sustainable design

Based on the advanced integrated technology of materials preparation and formation, a new pattern Zn-Al-Mg-RE anti-corrosion coating for steel structure sustainable design was manufactured by cored wires and high velocity arc spraying (HVAS) technologies. The developments of thermally sprayed coatings for steel structure protection were described. Based on Al, Zn, Zn-Al and Zn-Al-Mg coatings, the anti-corrosion properties of new-pattern Zn-Al-Mg-RE coating were evaluated through electrochemical methods including electrochemical polarization and electrochemical impedance spectroscopy (EIS) coupled with SEM and XRD. The models of Zn-Al-Mg-RE coating undergoing corrosion with the initial pinhole defect and the latter with accelerated products were also discussed. The results show that Zn-Al-Mg-RE coating exhibites excellent corrosion resistance for long-term immersion, which is helpful for the sustainable design of steel structure in aggressive corrosion conditions. And the corrosion products seem to possess certain self-sealing function. Foundation item: Project (50235030) supported by the National Natural Science Foundation of China