32Cr2MoV钢表面电泳沉积氧化铝和氧化锆涂层*

采用电泳沉积法以硝酸铝和硝酸钇为溶胶原料,在溶胶制备过程中加入钇稳氧化锆(YSZ),然后利用电泳沉积和热压滤烧结相结合方法在32Cr2MoV钢表面制备氧化铝和氧化锆涂层。用扫描电子显微镜(SEM)对涂层表面及界面形貌进行观察,利用X射线衍射仪(XRD)对涂层物相组成进行分析,采用热循环氧化试验研究涂层对基体在900℃空气中高温氧化行为的影响。结果表明,利用电泳沉积法在32Cr2MoV钢表面制备了一层致密陶瓷涂层,经热压滤烧结后涂层由表层α-Al2O3和ZrO2、次表层Fe的氧化物以及靠近基体的Fe、Mo、Cr氧化物层组成,经900℃热循环氧化试验表明,陶瓷复合涂层对基体32Cr2MoV钢起到了一定的抗氧化保护作用。     

溶胶-凝胶高温氧化防护涂层

溶胶-凝胶方法是一种制备氧化物涂层的简单方法.在不同基体上，采用溶胶-凝胶法可以制备连续的对基体起保护作用的SiO2、Al2O3、ZrO2及它们间复合的涂层.本文系统介绍了溶胶凝胶过程的特点、原理，着重介绍溶胶凝胶法制备抗氧化性涂层的工艺过程，分析了该方法存在的缺点，指出未来要解决的问题.并简单介绍了一种新型无氧溶胶-凝胶制备陶瓷涂层技术.      

溶胶-凝胶法制备陶瓷涂层封孔剂的研究

针对等离子喷涂陶瓷涂层中存在孔隙而使其耐蚀性能下降的问题,本文采用溶胶-凝胶法制备了氧化硅溶胶和氧化铝溶胶,并用这两种溶胶对等离子喷涂陶瓷涂层进行封孔处理。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、孔隙率测试及耐腐蚀实验对封孔处理后的涂层进行了测试分析。结果表明,氧化硅和氧化铝溶胶均对陶瓷涂层起到了一定的防护性能,从而提高了其耐蚀性能。     

纳米Fe3+-TiO2涂膜对多孔陶瓷性能的影响

采用溶胶-凝胶法制备了掺杂Fe3 离子的TiO2溶胶,并采用浸渍提拉法在多孔陶瓷上涂敷了该Fe3 -TiO2膜,研究了工艺条件对多孔陶瓷性能的影响.研究结果表明:溶胶的pH值及粘度、掺杂Fe3 离子的量和涂层次数等对多孔陶瓷的性能参数及光催化氧化性能有很大影响;当溶胶的pH值为3～4、溶胶粘度约6 mPa·s、掺杂Fe3 离子量为2.0 g/L左右、涂层次数为2～3次时,制备的多孔陶瓷具有良好的过滤性能和光催化氧化性能.     

溶胶-凝胶法制备纳米氧化铝粉末的研究

氧化铝在许多工业领域已经得到了广泛的应用，随着新材料科学和先进制造技术的发展，对陶瓷复合材料的性能要求日益提高，为了提高氧化铝基陶瓷复合材料的力学性能，需要提高氧化铝的纯度和表面活性、降低其粒度，对此传统的氧化铝制备方法不能满足这一要求。溶胶一凝胶法是制备纳米粉末的重要技术之一，作为一种湿化学合成方法，具有设备简单，工艺易于控制，粉末纯度和均匀度高，成本低等优点，在制备涂层以及涂层复杂形状零件方面有很大的优越性。本文以异丙醇铝(Al(C3H7O)3)为原料，用溶胶--凝胶法制备出了纳米氧化铝(Al2O3)粉末。通过x射线衍射分析和差热分析，研究了由凝胶至α-Al2O3，粉末的转变过程以及影响粉末性能的因素。研究表明，溶胶--凝胶法制备的胶体在1200℃的温度下可以完全转化为纳米α-Al2O3，并且具有较高的质量密度，所制备的纳米α-Al2O3，具有较理想的晶体结构类型，未发现其它相或杂质，这表明溶胶--凝胶法是制备高纯度纳米陶瓷粉末的有效技术。     

钢基体涂覆Al2O3陶瓷层的研究现状与展望

综述了目前钢基体上制备Al2O3陶瓷涂层的研究现状，详细介绍了热喷涂法、溶胶一凝胶法及热化学反应法3种制备Al2O3陶瓷涂层的主要方法，并探讨和分析了它们各自的优缺点。热喷涂法普遍存在维护和使用费用昂贵的特点；溶胶一凝胶法最大优点就是制备过程温度低；热化学反应法作为一种新兴的钢基Al2O3陶瓷涂层制备方法，其显著优点在于工艺简单、成本低廉并且无需特殊设备，具有广阔的发展前景。文章最后对Al2O3陶瓷涂层的研究进行了展望。     

溶胶-凝胶制备的Al_2O_3-SiO_2复合陶瓷涂层抗原子氧侵蚀性能研究

采用溶胶-凝胶法,以异丙醇铝、正硅酸乙酯为原料制得了稳定、均一的溶胶,浸涂在聚酰亚胺表面干燥后获得了致密透明的涂层.采用空间综合环境地面模拟设备对试样进行了原子氧(Atomic Oxygen, AO)暴露实验.测试表明,溶胶-凝胶制备的Al_2O_3-SiO_2涂层抗原子氧侵蚀性能优异,抗原子氧侵蚀性能比聚酰亚胺基体提高了2个数量级以上.经原子氧暴露后的复合陶瓷涂层质量几乎没有发生变化.经FTIR和XPS分析表明,在原子氧暴露后涂层表面产生的是Al_2O_3-SiO_2复合物.SEM分析表明,无涂层的聚酰亚胺原子氧暴露后表面非常粗糙且表面呈现地毯状形貌,而涂覆涂层的试样暴露前后表面形貌没有发生变化.采用紫外-可见光-近红外分光光度计对涂覆溶胶-凝胶复合陶瓷涂层后的试样分析表明原子氧暴露前后试样表面的光学性能也未发生变化.     

溶胶-凝胶法制备Al2O3·ZrO2复合陶瓷涂层研究

用溶胶-凝胶(Sol-gel)法以Al(NO3)3·9H2O,ZrOCl2·8H2O为原料,乙醇为溶剂,在不锈钢表面制备了xAl2O3·yZrO2复合陶瓷涂层.研究了基材氧化预处理、溶液纽成、添加剂等对陶瓷涂层组成、性能的影响.结果表明:基材氧化预处理能大大改善涂层与基材的结合强度:涂有xAl2O3·yZrO2陶瓷涂层的材料具有较不锈钢更优良的抗高温氧化性能.     

TC4钛合金微弧氧化-溶胶凝胶复合涂层的制备及其抗高温氧化性能

为了提高钛合金的使用温度,设计并制备了一种微弧氧化(MAO)-氧化钇稳定氧化锆(YSZ)的陶瓷复合涂层。采用微弧氧化(MAO)技术在TC4钛合金基体表面原位生长出一层氧化铝陶瓷层(TM涂层),然后采用溶胶-凝胶法(Sol-gel)在MAO层的基础上制备低导热系数的钇稳定氧化锆(YSZ)涂层,最终制备出MAO-YSZ复合涂层(TMY复合涂层)。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和能谱仪(EDS)分析涂层的相结构、组织形貌和成分,并测定了TC4、TM涂层以及TMY复合涂层在700℃下的氧化动力学曲线。结果表明:TMY复合涂层外层以ZrO2为主,内层主要为Al2O3。具有TMY复合涂层的钛合金在700℃下氧化100h后其氧化增重仅为无涂层钛合金的14%,说明TMY复合涂层可以显著提高钛合金的抗高温氧化性能与使用温度。     

经溶胶-凝胶后处理之热障涂层的热传导行为特性

热障涂层已广泛用于若干工业部门。在这些系统中用作隔热体的材料是等离子喷涂在金属粘结底层上的经部分稳定化处理的氧化锆 (PSZ)。陶瓷涂层通常是疏松多孔的 ,这样就改善了隔热性能 ,但孔隙也同时增加了气体的可穿透性 ,因此降低了涂层的抗氧化性能。应用后处理可以减少开放式孔隙从而改善抗氧化性。本研究是在采用两组粘结底层即金属涂层和金属 -陶瓷涂层的低碳钢基体上应用热障涂层。金属粘结底层是NiCrAlY ,而金属-陶瓷粘结底层是NiCrAlY和用 8%氧化钇部分稳定化的氧化锆的混合物 ,用两个送粉器同时将它们输送到等离子喷枪中。溶胶 -凝胶法是用氧化铝和氧化锆浸渗填满陶瓷顶涂层中的孔隙。用水银浸入孔隙率仪 (MIP)和热传导性能评价了喷涂态的和后处理状态下的涂层试样     

涂层用Al2O3-ZrO2复合浆料的制备

为了在金属表面制备良好的陶瓷涂层,以异丙醇铝、硝酸、蒸馏水为原料制作了铝溶胶,在铝溶胶中加入氧化锆,制成涂层用复合浆料。采用DTA,XRD和沉降实验等方法对复合浆料进行了分析,结果表明:溶胶制备时应控制pH为2;异丙醇铝和蒸馏水的摩尔比为1∶80;复合浆料中氧化锆的合适配比为85%~90%(体积分数);复合浆料的烧结温度为830℃。     

Protection of titanium metal by nanohydroxyapatite coating with zirconia and alumina second phases

In this study hydroxyapatite (HA)/zirconia/alumina composite coatings on titanium metal was carried out using Sol-Gel dip coating and calcination process. Hydroxyapatite-Alumina-Zirconia sol, coated samples in three processes by changing final sol stirring time, aging time, calcination temperature of synthesized powder and prepared coating and rate of coating. Some parts of prepared sol were also synthesized and became powder in all three processes. Scanning electron microscopy was used to estimate the particle size of the surface and for morphological analysis. The functional group and crystallization characteristics of the powders were analyzed using (FTIR) and X-Ray diffraction (XRD). Results show that the morphology of HA-Alumina-Zirconia coatings is more homogenous in the second process with 2 hours final sol stirring time, 20 hours aging time under stirring at 60, 675°C calcination temperature for coating and 850°C for powder and 60mm/min rate of dip coating.     

Manufacturing of Porous Alumina Ceramic by Gel Casting

Various quantities of non-toxic monomer (2-hydroxyethyl methacrylate, HEMA) was added to form porous alumina ceramic by gel casting process. Pure water, monomer, cross-linker (N, N'-methylene-bis-acrylamide (MBAm)), and dispersant (ammonium salt of poly (methacrylic acid), PAS) were combined to form an aqueous solution, which added alumina powder and was milled to form alumina slurry with zirconia balls for 240 minutes. An initiator (ammonium persulfate, APS) was added to the alumina slurry with a vacuum mi...     

Post-deposition treatment of zirconia thermal barrier coatings using Sol-Gel alumina

This article addresses the problem of gas permeability of thermal sprayed yttria-stabilized zirconia thermal barrier coatings (TBC)s. The objective of this study was to decrease the open porosity of TBCs through deposition of dense alumina ceramic on the surface of the pores. A simple infiltration technique was used, beginning with aluminum isopropoxide as sol precursor, subsequently hydrated to aluminum hydroxide sol, which decomposed at relatively low temperatures to extra-fine, readily sinterable aluminum oxide. In some experiments, the sol-gel (SG) precursor was combined with fine grains of calcined alumina, constituting high solid-yield composite sol-gel (CSG) deposits within the pores of TBCs. Sinterability in the model systems, including aluminum hydroxide sol-calcined alumina and aluminum hydroxide sol-calcined alumina-zirconia, has been studied. A number of TBC specimens were impregnated with suspensions of alumina sols and CSG. It is shown that these ceramics effectively penetrated into the pores and cracks of TBCs and reduced the coating permeability to gases. The overall reduction of porosity was however small (from ∼12 to ∼11%), preserving the strain and thermal shock tolerance of the coatings. Burner rig tests showed an increase in sealed coating lifetime under thermomechanical fatigue conditions.     

送粉激光熔覆ZrO2/Ni60复合涂层组织结构与性能

采用送粉激光熔覆工艺分别制备了含1％和3％氧化锆陶瓷的强韧化镍基自熔合金涂层，考察了氧化锆含量，以及工艺参数对熔覆层组织结构与性能的关系。结果表明，氧化锆掺杂涂层的组织特征取决于熔池的流动性，由于氧化锆的密度较镍基自熔合金要小许多，因此在激光束提供的能量超过一定值之后，会出现分层的组织结构，反之可获得均匀的两相复合组织结构。最后给出了获得均匀组织结构的工艺方案。     

Comparison in characterization of composite and sol-gel coating on AZ31 magnesium alloy

An Al2O3 protective coating on magnesium alloy AZ31 was prepared by a repeated direct sol-gel process annealing at 300℃and a composite coating was also deposited using Al2O3 particles dispersed sol followed by phosphating treatment and annealing at 300℃.The morphologies,structures and critical adhesive loads as well as corrosion properties of the coatings were comparatively investigated by scanning electron microscopy(SEM),X-ray diffractometry(XRD),nanoscratch test and electrochemical measurement.The results show that the composite coating has a more uniform,crack-free layer and improved adhesion to the substrate as compared with that of the repeated direct sol-gel coating owing to its lower heat strain.The main phases in both coatings consist ofγ-Al2O3 andδ-Al2O3 derived from annealed alumina sol,and the composite coating has an anticorrosion performance which is superior to that of the repeated direct sol-gel coating.     

Effect of Ni–P and Phosphate Intermediate Layers on Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Coating Developed by Sol-Gel Method

Sol–gel method was used for applying of alumina coating on carbon steel substrate. Alumina sol was prepared with Al-isopropoxide as a precursor material. Specimens were coated with prepared alumina sol by dip coating technique. Either a film of Ni–P or phosphated intermediate layer has been pre-deposited on the carbon steel substrate by electroless plating to improve the adherence of alumina coating. The corrosion resistance of coatings in the presence of intermediate layers was evaluated by electrochemical measurement in 3.5% NaCl solution by open-circuit potential measurement at room temperature. The abrasive wear behavior of sol–gel coated specimens was measured in high stress conditions. The results indicate that, after applying an intermediate layer of phosphate or Ni–P by electroless plating technique, the wear and corrosion resistance of alumina coating have been improved. Moreover, the phosphate intermediate layer has been associated with a higher corrosion resistance, while the intermediate layer of Ni–P is more effective to improve the hardness and wear resistance of alumina coating.     

MoSi2-硼硅玻璃鳞片状高发射率耐高温涂层

为了从本质上改变传统高辐射率耐高温涂层刚度大、脆性明显的问题,受自然界中蛇皮结构的启发,将浆料法与溶胶-凝胶法相结合,采用硅溶胶作为溶剂,MoSi2作为发射剂,硼硅玻璃作为高温粘结剂,制备出具有鳞片状结构的柔性高发射率耐高温涂层。与组成、面密度以及烧结制度相同的致密涂层相比,鳞片状涂层在保障其高的发射剂含量与发射率的同时,具备了非常高的柔韧性,其抗接触损伤、抗热震以及抗弯曲强度等多个力学性能均得到了不同程度幅度的提升。     

化学镀钴-磷-氧化锆复合镀层的研究

采用化学镀法制备钴-磷-氧化锆复合镀层，并研究了PH值、温度、氧化锆的加入量、氧化锆的粒度和后处理等制备工艺条件对沉积速率、镀层的空隙率、硬度争性能的影响。试验结果表明，制备钴-磷-氧化锆复合镀层的最佳工艺条件为85℃-90℃、PH值9左右，采用空气搅拌或电磁射觉拌。加入细的ZrO2颗粒不仅可以细化镀层的组织结构，而且还可以提高镀层硬度等性能。所获得的复合镀层经400℃热处理后，显微硬度还可进一步提高。