纳米Ti0.8Cr0.2OxNy粉体的制备与表征

以沉淀法制备的纳米TiO2／Cr2O3复合粉体为原料，采用氨解法在800℃、氮化8h制备了纳米Ti0.8Cr0.2OxNy粉体．对纳米TiO2／Cr2O3复合粉体和合成的氧氮化物粉体用俄歇电子能谱(AES)、氮吸附比表面积(BET)、X射线衍射(XRD)、透射电子显微镜(TEM)、电子探针显微分析(EPMA)等方法进行了表征．结果表明：沉淀法可以制备出组成均匀的纳米TiO2／Cr2O3复合粉体，该复合粉体在800℃氮化8h可得到粒度为20～30nm的纯立方相Ti0.8Cr0.2OxNy纳米粉体，其比表面积达46．74m^2／g．     

Absorbing properties investigation of SrFe12O19-NiFe204 composite nanopowders with core- shell structure

以Fe（NO3）3、Ni（NO3）2和Sr（N0s）2为主要原料,通过两步柠檬酸盐溶胶一凝胶法,制备出核一壳结构SrFe12O19-NiFe2O4磁性纳米复合粉体。采用XRD、TEM、VSM及矢量网络分析仪对合成的粉体的结构、形貌及吸波性能进行了分析研究。结果表明,复合粉体的相结构与NiFe2O4含量有关,当SrFe12O19与NiFe2O4的质量比为1：2、烧结温度为1050℃时,复合纳米粉体的相与NiFe2O4接近,核一壳结构SrFe12O19-NiFe2O4纳米复合粉体的饱和磁化强度（Ms）（51．4emu／g）比单体SrFel201。纳米粉体（42．6emu／g）的大;但矫顽力（H。）（336Oe）比单体SrFel2019纳米粉体的小,在SrFel2019与NiFe204的矫顽力5395-160Oe之间。在频率为8-18GHz范围内,微波吸收逐渐增强,当频率为12GHz时,SrFe12O19-NiFe2O4纳米复合粉体的微波吸收达到最大值-9．7dB,是一种性能优良的吸波材料。     

Li2MnO4的制备和性能研究

以LiNO3和Mn（NO3）2为原料，尿素为燃烧剂，采用燃烧合成方法制备了LiMn2O4粉体。通过X衍射（XRD）和扫描电镜（SEM）确定了LiMn2O4粉体的结构和微观形貌；采用热重分析（TGA）和差热分析（DTA）研究了LiMn2O4的反应过程；通过合成影响因素的试验研究找出了尖晶石LiMn2O4燃烧合成的最佳条件。     

纳米Cr_2O_3粉体的制备及表征

以Cr(NO_3)_3·9H_2O、氨水和乙醇为原料,采用沉淀法在不同温度下合成了纳米Cr_2O_3粉体,并运用场发射扫描电镜、X射线衍射、热重-动态差热分析、红外光谱等手段对粉体进行表征。结果表明,Cr(OH)_3在450℃已经生成Cr_2O_3,经过800℃煅烧30min可获得平均粒径为70～100nm的Cr_2O_3粉体。     

铬掺杂对PZN-PZT陶瓷微观结构和电学性能的影响

研究了Cr2O3掺杂对0．2Pb（Zn1／3Nb2/3）O3-Pb（Ti0.5Zr0.5）03（PZN-PZT）陶瓷结构和电学性能的影响。结果表明,Cr2O3掺杂量小于0．3wt％时,Cr2O3能引起三方-四方相变,四方相含量诸加,晶粒尺寸和烧结密度上升;掺杂量高于0．3wt％时,Cr2O3掺杂能抑制晶粒长大并降低烧结密度。同时,Cr2O3掺杂表现出硬性掺杂特征：εr变小,Qm值增加。而tanδ,kp和d33随Cr2O3掺杂量增加而表现出极值特征。最佳的压电性能出现在Cr2O3掺杂量为0．3wt％处。     

共沉淀法制备ZrO2-Al2O3-CeO2的煅烧反应过程及物相表征

以氨水为沉淀剂，采用共沉淀法按一定比例分别制备了ZrO2-Al2O3-CeO2、ZrO2-Al2O3-CeO2、ZrO2-Al2O3-CeO2等4种前驱复合粉体。利用差热-热重分析（DTA/TG）和X射线衍射（XRD）对4种粉体的热转变过程以及不同温度煅烧后的物相组成进行了对比分析，研究了ZrO2-Al2O3-CeO2复合粉体间在煅烧过程中的化学反应及相互影响。结果表明：CeO2与ZrO2优先形成固溶体，CeO2与Al2O3直到1300℃也未发生任何反应；Al2O3的存在明显提高了c-（Ce，Zr）O2的结晶温度，1300℃退火后t-（Ce，Zr）O2仍能保留到室温。     

纳米Cr2O3对环氧涂层耐腐蚀性的影响

利用燃烧法制备粒径为10-20 nm的球状纳米Cr2O3。将纳米Cr2O3粉体添加到环氧涂层中,根据电化学阻抗谱和盐雾试验研究Nano-Cr2O3对环氧涂层耐蚀性的影响。结果表明,Nano-Cr2O3可显著提高环氧涂层耐蚀性。Nano-Cr2O3主要在涂层中提高涂层耐蚀性起到两方面作用:一是减少了孔隙率,增加了涂层的物理屏蔽作用;二是Cr3+离子直接与溶液中腐蚀热镀锌所产生的Zn2+、OH-离子反应,生成了不溶性的Zn Cr2O4隔离层。     

沉淀-氨解法制备超细高纯氮化铬粉体

以氨水直接沉淀法制备的纳米Cr2O3为前驱体,采用氨解法制备了纯度99%以上的高纯超细CrN粉体。对不同氨解温度、氨解时间和不同前驱体合成的CrN粉体用XRD、SEM和氮/氧分析等方法进行了表征。对CrN粉体合成的原理及其主要影响因素进行了分析,并研究了不同前驱体、不同氮化温度和不同氮化时间对CrN粉体性能的影响。结果表明,将氨水直接沉淀法制备的Cr2O3粉体在800℃下利用氨气氮化12h可得到纯度99.15%高纯超细氮化铬粉体,粒径大小约为0.2μm左右。     

Pb(Zr0.95Ti0.05)O3粉体的冲击波合成及烧结研究

以ZrO2、Pb304和TiO2为原料（Nb2O5为掺杂剂）,采用柱面冲击波装置合成了Pb（Zr0.95 Ti0.05）O2（PZT95／5）粉体,并对粉体活性及其烧结性能进行了研究。XRD及SEM分析表明,利用冲击波的高温高压作用可以合成单一钙钛矿相PZT95／5粉体,并使得粉体发生了晶粒细化与晶格畸变,这有利于增强粉体活性,促进低温活化烧结。该粉体在1100℃的低温下即可烧结成瓷;在1200℃烧结3h,陶瓷体致密度达到最大,约7．79g／cm^3,且晶粒尺寸相近,分布均匀。     

焙烧工艺对超细γ—Al2O3粉体分散稳定性的影响

采用醇盐水解法制备超细γ-Al2O3粉体，利用同步热分析仪分析γ-Al2O3前驱体中溶剂分解、晶型转变，采用X射线衍射仪、BET（（Bmnauer-Emen-Teller）、扫描电镜等表征了超细γ-Al2O3粉体的晶型结构、组成及其宏观物性，重点探讨了焙烧工艺对超细γ-Al2O3粉体分散稳定性的影响。结果表明，在空气气...     

Oxidation‐Resistant Coatings for Application on High‐Temperature Titanium Alloys in Aeroengines

High‐temperature application of titanium alloys in aeroengines is often limited by their insufficient resistance to the aggressive environment. Magnetron‐sputtered Ti–Al based coatings were developed in order to increase the maximum service temperature of conventional titanium alloys from the present 520–600 °C, the temperature limit set by the mechanical capabilities of most advanced alloys. The coatings not only demonstrated excellent oxidation resistance but also demonstrated beneficial effects on mechanical properties. Most importantly, the fatigue behavior of the substrate alloys was not degraded, a major hurdle for coating application on titanium alloys so far. Initial results on Cr‐containing Ti–Al based coatings indicated significant potential for application on titanium aluminides.     

钛合金表面微弧氧化技术的研究

微弧氧化是一项在有色金属表面原位生长陶瓷膜的新技术,利用该技术可在钛合金表面生成耐磨、耐蚀、耐高温以及电绝缘性能优异的陶瓷膜层.介绍了微弧氧化技术的基本原理、钛合金微弧氧化的发展及现状,并提出了钛合金表面微弧氧化技术发展的新思路.     

Research status of laser cladding on titanium and its alloys: A review

Titanium and its alloys are restricted in the field of application. Laser cladding, as a kind of surface modification technique, is employed to fabricate coatings with improved wear resistance, high temperature oxidation resistance and good biocompatibility on titanium and its alloys. Apart from laser cladding process parameters, material selection is vital to obtain the improved properties mentioned above. In this paper, recent developments of different material system are summarized and the developments in laser cladding for functional coatings with high wear resistance, good corrosion and oxidation resistance, and better medical biocompatibility are reviewed. Besides, the existing problems and the corresponding solutions are discussed. Finally, the trend of development in the future is forecasted.     

电解液和电参数对钛合金微弧氧化的影响

结合实验研究,系统介绍了钛合金微弧氧化过程中电解液、电参数的选择,以及其对微弧氧化陶瓷层的结构和性能的影响,并指出利用微弧氧化技术可以在TC4合金表面制备出结构陶瓷层和功能陶瓷层,在航空航天等领域有广阔的应用前景.     

Basic Concepts for better heat protection systems

The mechanisms of oxide growth and adhesion on high temperature resistant alloys are discussed. Routes for achieving superior oxidation resistance are outlined. The hot corrosion resistance of high temperature alloys seems to be related to the respective oxide adhesion of the protective oxides on them. Ceramic coatings on metals offer additional heat and corrosion protection which can be markedly improved by matching the thermal expansion coefficients (TEC) of substrates to that of dense ceramic coatings.     

钼及其合金氧化防护涂层的研究进展

钼及其合金具有较好的高温力学性能和良好的耐腐蚀性能,然而高温氧化问题限制了钼及其合金的应用。分别从涂层体系、涂层结构及涂层的制备工艺3个方面综述了近年来国内外钼及其合金氧化防护涂层的研究进展。在涂层体系方面,目前的研究主要集中在钼的硅化物(如MoSi2涂层)上;在涂层结构方面,对比了各种结构涂层的特点,单一涂层与基体存在热膨胀不匹配问题,使得单一涂层作为高温防护的应用受到限制,然而复合涂层却明显改善了此缺点;在涂层的制备工艺方面,介绍了涂层的各种制备工艺及其优缺点。综合应用各种涂层制备工艺,发展新型复合涂层是今后钼及其合金氧化防护涂层的发展方向。     

Nb掺杂对Ti-Al合金化层抗高温氧化性能的影响

为提高钛合金TC4的抗高温氧化性能,采用激光表面合金化技术在钛合金表面制备不同Nb掺杂量的Ti-Al合金化层。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能谱仪(EDS)、箱式电阻炉等对合金化层的组织结构和高温氧化行为进行分析测试。结果表明,合金化层主要组成物相为TiAl以及少量的Ti_3Al相。Nb主要以置换溶质原子的形式固溶于合金化层中。合金化层组织均匀,与基体呈典型的冶金结合,在不含Nb的Ti-Al合金化层中发现大量的表层裂纹及少量的贯穿性裂纹,而在Nb掺杂的合金化层中未发现明显的宏观裂纹。合金化层在800℃保温1000h的氧化增重显著低于基体,表现出优异的抗高温氧化性能。相比而言,随着Al含量和Nb掺杂量的提高,合金化层的抗高温氧化能力也随之提高。Nb掺杂提高Ti-Al合金化层抗高温氧化性能的作用机理包括减少TiO_2中的空位缺陷、细化氧化物颗粒及促进Al_2O_3的形成。     

Zunderverhalten und Ausscheidungshärtung von hochkarätigen Gold-Titan-Legierungen

The behaviour of oxidation and precipitation hardening of very goldrich gold-titan alloys The oxidation behavior of gold rich Au-Ti alloys with contents of titanium between 0.5 und 1.3 weight-% was investigated in synthetic and natural air in dependence on the oxidation temperature and time. A closed homogeneous layer of titanium oxid was not formed. The nucleation of TiO₂ (Rutil) starts at prefered sites (grain boundaries, structure defects) below the surface of the alloys. The precipitations grow without formation a gapless cover of the grain boundaries. Between the precipitations the concentrations of titanium and oxygen are zero. The titanium is transported out of the interior of the specimen by volume diffusion. Based on an experimentally observed linear relationship between the oxygen uptake and the oxidation time the speed constants could be determined for 750°C, 825°C and 900°C. Between the natural logarithm of the speed constant and the reciprocal temperature a linear connection exists. For this reason it is possible to calculate the kinetics by a well-defined mathematical expression for the speed constant of the titanium oxidation in dependence on the titanium content and the oxidation temperature. The connection between the speed constant and the optical outfit of the surface is illustrated. Furthermore the precipitation hardening of the alloys at temperatures between 100°C and 700°C is described. A noticable increase of the hardness is already produced at relatively low temperatures. Whith increasing temperatures the hardness maximum is shifted to shorter times. With increasing titanium content the hardness maximum increases and it is obtained after shorter times. Cold working before the ageing, raises the hardness maximum and accelerates the precipitation. The precipitations are formed to little plates with high coherency to the matrix preferentialy at the grain boundaries. X-ray analysis sensitively responds to the kinetics of precipitation and gives reliable information about the concentration variations of the matrix. The results concerning the oxidation behavior and the precipitation hardening make it possible to find the conditions of an optimized heat treatment with high hardness but without negative changes of the surface.     

Role of rare earth oxide coatings on oxidation resistance of chromia-forming alloys

Rare earths (RE) have been used to increase high temperature oxidation resistance of chromia and alumina forming alloys. The RE can be added as elements (or oxides) to the alloys or applied as oxide coatings to the alloy surface. This paper presents the effect of different RE oxide coatings and lanthanum chromite coatings on the high temperature oxidation behavior of Fe20Cr and Fe20Cr4Al alloys. The oxidation resistance of the Fe20Cr alloy increased with increase in ionic radius of the RE element in the coating. The RE oxides decreased chromia growth rate more than alumina growth rate. In extended cyclic oxidation tests that were carried out from peak temperatures of 900 °C, 1,000 °C and 1,100 °C to room temperature at cooling rates of 300 °C/s and 1,000 °C/s, the La₂O₃ coating increased cyclic oxidation resistance of the Fe20Cr alloy significantly more than the Pr₂O₃ coating. The role of RE in increasing overall oxidation resistance of chromia forming alloys is discussed.     

钛合金表面耐磨润滑微弧氧化膜的研究进展

综述了钛合金微弧氧化膜的摩擦学性能研究以及提高膜层耐磨性能和润滑性能所采用的方法,旨在对改善钛合金微弧氧化膜摩擦学性能的研究现状有一个系统全面的认识,并在此基础上展望了未来钛合金微弧氧化膜摩擦学研究的发展趋势和方向。