电泳沉积纳米二氧化钛陶瓷涂层结构表征与性能研究

电泳沉积法(EPD)制备薄膜具有设备简单,成本低,成膜快,被镀件(用于沉积薄膜的基体)形状不受限制,薄膜厚度均匀,并且其厚度在较大范围内可控等优点。二氧化钛熔点高、化学稳定性好,在复合材料领域具有广阔的应用前景。笔者利用电泳沉积法制备出了均匀的二氧化钛薄膜,研究了二氧化钛在悬浮介质中的核电机理;考察了二氧化钛粉末在有机悬浮液中的分散性和稳定性,并且研究了电泳工艺参数对电泳沉积量的影响;特别研究了助剂PEG(聚乙二醇)对电泳膜性能的影响并初步探讨了助剂PEG对二氧化钛膜性能影响的原因;研究了电泳沉积的动力学规律,为今后制备含二氧化钛的层状复合材料打下基础。笔者还通过研究不同的烧结温度对二氧化钛晶型的影响且定性的表征了光催化性能。     

电泳沉积法制备固体电解质薄膜的沉积速率和沉积机理

研究了用电泳沉积法制备含钇８末在悬浮介质中的荷电机理;采用界面移动法测定了８ＹＳＺ粉末在有机悬浮液中的电泳淌度和ξ电势,研究了ξ电势的影响因素;考察了８ＹＳＺ粉末在有机悬浮液中的分散性和稳定性;研究了电泳沉积的动力学规律,确定了电泳沉积过程的速度控制步骤,推导出电泳沉积速率方程．利用重复沉积－烧结法制备的致密化薄膜厚度为２６～５６μｍ,硬度为４．３３ＧＰａ,在１０００℃时Ｏ－２电导率为１２．２Ｓ／ｍ,电导激活能为１．０９ｅＶ．     

不同制备方法下的La0.8Ca0.2MnO3巨磁阻薄膜的形貌特征研究

采用了固相粉末烧结法、脉冲激光沉积法(Pulsed Laser Deposition)和溶胶—凝胶法(sol—gel)3种方法,制备出了La0.8Ca0.2MnO3(LCMO)巨磁阻粉末样品和在硅基底上诱导生长的薄膜样品。用原子力显微镜(AFM)、光学显微镜以及X射线衍射(XRD)对所得样品进行了结构表征。系统地研究了热处理条件对LCMO结晶形貌的影响。结果发现硅基底上的LCMO薄膜因受到诱导从而呈现出定向生长的现象,表现为类似“花”状的形态;对于固相法制备的样品,则呈现出无定型的多晶形态;对于脉冲激光沉积法制备的样品呈现出均匀致密的多晶薄膜。     

氮化硅薄膜生长随时间演化过程及其特性研究

氮化硅SiN_x薄膜凭借介电常数高和稳定性好的特点而被广泛应用于光电器件中,但薄膜的厚度对器件的性能有重要影响。针对此问题采用等离子体化学气相沉积技术,以高纯NH₃、N₂和SiH₄为反应气体,优化其他沉积参数,通过改变沉积时间来生长SiN_x薄膜。用X射线衍射谱(XRD),紫外-可见光光谱(UV-VIS)、傅里叶变换红外光谱(FTIR)和扫描电镜(SEM)对薄膜结构进行表征,详细研究了沉积时间与薄膜厚度的关系以及沉积时间对薄膜性能的影响。试验结果表明:所制备的样品为非晶SiN_x薄膜结构,薄膜厚度随沉积时间均匀增加;薄膜折射率随沉积时间的增加而增大,光学带隙基本不随时间变化。SEM测试结果表明,随着沉积时间增加,薄膜致密性与均匀性越来越好,氧含量也越来越少,说明薄膜致密性提高可以有效阻挡O原子进入薄膜,阻止后氧化现象的发生。     

铜基板法制备纳米碳纤维薄膜的研究

以乙炔(C2H2)作为碳源,采用化学气相沉积法(CVD)在经过草酸溶液腐蚀的铜基板表面制备出纳米碳纤维薄膜。采用扫描电子显微镜(SEM)和X射线粉末衍射仪(XRD)对产物进行结构与形貌表征,并对碳纤维薄膜进行其在基板上的附着性测试。结果表明,草酸腐蚀时间、化学气相沉积反应时间的变化等因素对纳米碳纤维薄膜的生长与形貌有一定影响。在反应温度为350℃时,铜基板表面制备出了一层均匀的纳米碳纤维薄膜,纤维直径为300~400 nm,薄膜的厚度为20~30μm。制备的纳米碳纤维薄膜对基板有良好的附着性。     

掺钇氧化锆薄膜的制备方法及应用研究新进展

介绍了掺钇氧化锆(YSZ)薄膜的制备方法,这些方法包括化学气相沉积法、电化学气相沉积法、电泳沉积法、溶胶-凝胶法、溅射法、流延成型法和等离子喷涂等,并评述了这些方法的优缺点;介绍了YSZ薄膜作为重要的功能材料在气体、液体分离与纯化、高温催化膜反应器、燃料电池和功能涂层等方面的应用;指出了未来YSZ薄膜应用研究的发展趋势。     

PVP与PVA对原位聚合导电聚苯胺薄膜的影响

分别以水溶性高分子聚乙烯吡咯烷酮(PVP)和聚乙烯醇(PVA)为稳定剂,采用苯胺的分散聚合体系,在玻璃基片上原位沉积了表面光滑均匀、亚微米厚度的导电聚苯胺薄膜,改善了导电聚苯胺的加工性能。研究了薄膜的形貌、厚度及电导率。结果表明:聚苯胺薄膜表面光滑,黏附一些胶体粒子,以PVP为稳定剂制备的聚苯胺薄膜表观质量好于以PVA为稳定剂得到的聚苯胺薄膜,表面更加光洁致密;不同稳定剂影响聚苯胺薄膜厚度及性能,在其他实验条件相同的情况下,以PVA为稳定剂制备的聚苯胺薄膜厚度及电导率均高于以PVP为稳定剂制备的聚苯胺薄膜厚度和电导率。     

金属有机化学气相沉积法制备Al掺杂ZnO透明导电膜

采用自行开发的金属有机化学气相沉积(metal organic chemical vapor deposition,MOCVD)法,以乙酰丙酮锌和乙酰丙酮铝分别为锌源和铝源,以氮气为载气,在玻璃衬底上制备Al掺杂ZnO(Al-doped ZnO,ZAO)薄膜。通过改造MOCVD设备提高制备薄膜的稳定性和均匀性,研究了基片温度、载气流量、水蒸气等沉积条件对薄膜结构,沉积速率及其光、电性能的影响。用扫描电子显微镜、X射线衍射、紫外-可见分光光度计和四探针双电测电阻仪分别观察薄膜形貌结构,并测试其光、电性能。结果表明:薄膜为均匀、致密的纳米多晶薄膜,具有六角纤锌矿结构,且呈c轴择优取向生长;薄膜的(002)衍射峰与纯ZnO相比向低角度方向偏移,表明Al进入了ZnO晶格,并导致晶格膨胀;薄膜的紫外-可见光谱透过率在85%以上;电阻率最小可达10-4??cm。     

化学浴沉积硫化铅薄膜及其晶体结构

采用化学浴沉积法(CBD)在玻璃衬底上制备了PbS薄膜,探究了沉积时间(20～100 min)对其厚度、微观形貌、晶体结构和禁带宽度的影响.结果表明,化学浴沉积所得的PbS薄膜均匀、致密,呈镜面光亮的黑色.随着沉积时间的延长,PbS薄膜厚度先快速后缓慢增大,微观形貌逐渐由片状结构转变为立方体结构,择优生长取向从(200)转变为(220),禁带宽度先减小后增大.沉积60 min所得PbS薄膜的厚度约为853 nm,以(220)晶面为生长取向,禁带宽度为0.205 eV,光学性能最佳.     

碳化钛/聚酰亚胺高介电复合薄膜的制备及性能研究

采用机械共混法将经硅烷偶联剂改性的碳化钛粉体掺杂入聚酰亚胺中,制备了碳化钛/聚酰亚胺复合薄膜。分析了不同碳化钛粒子含量对复合薄膜的显微结构、力学性能及介电性能的影响。实验结果表明,随着纳米TiC含量的不断升高,复合薄膜的拉伸强度呈现先上升后下降的趋势,复合薄膜的耐电击穿场强迅速下降。与此同时,复合材料的介电常数则显著提高。     

C/C composite surface modified by electrophoretic depositing SiC nanowires and its brazing to Nb

A novel surface treatment method by electrophoretic depositing SiC nanowires on the C/C composite was introduced to reinforce the C/C–Nb brazed joints. Results showed that the electrophoretic deposition (EPD) process of SiC nanowires could improve the wettability of the liquid AgCuTi alloy on the C/C substrate because of the reaction between SiC nanowires and active element Ti in the AgCuTi alloy. With the introduction of SiC nanowires, the formation of continuous brittle Ti₃Cu₄ layer was inhibited and the Ti₃Cu₄ changed into lumps. The thickness of the TiC reaction layer was 500 nm when the EPD time was 5s which was larger than that of the original brazed joint. As the EPD time continued to increase, the thickness of the TiC reaction layer decreased gradually and the size of brittle Ti₃Cu₄ phase in the joint became smaller and smaller. With the combined effects of the change in the Ti₃Cu₄ morphology and the TiC reaction layer thickness, the average shear strength of joints achieved a peak of 48 MPa when the EPD time was 30s, which was 60% higher than that of the original brazed joints.     

TiC粉体合成的研究现状与展望

TiC具有高熔点、高硬度、高化学稳定性、高耐磨性等优良性能,在多个行业具有广阔的应用前景。目前合成TiC粉体的方法较多,本文综述了碳/金属热还原法、熔盐辅助合成法、机械合金化法等几种主要合成方法,并分析了各种合成方法的优缺点,可为低成本、大规模合成高纯度、形貌可控的TiC粉体提供参考,还对TiC粉体未来合成研究进行了展望。     

Optical and adhesive properties of composite silica-impregnated Ca-α-SiAlON:Eu2+ phosphor films prepared on silica glass substrates

The compaction of a Eu-doped Ca-α-SiAlON phosphor powder was performed by electrophoretic deposition (EPD). The effect on the adhesion and optical properties of the silica precursor as both a binder of the powder and a filler of the air voids were evaluated. The adhesion of the silica impregnated composite film to the silica glass substrate was characterized by the tape test. The improvement of the external quantum efficiency was confirmed from the PL spectra measurement after the silica impregnation. The temperature dependence of the external quantum efficiency was also investigated in order to discuss the advantage of using the silica precursor as a binder for high-brightness LED applications.     

Multi-walled carbon nanotube/polyimide composite film fabricated through electrophoretic deposition

Multi-walled carbon nanotube (MWCNT)/polyimide composite films were fabricated through electrophoretic deposition (EPD) of MWCNT-polyamic acid colloidal suspension which was derived from carboxylated-MWCNTs and poly(pyromellitic dianhydride-co-4,4′-oxydianiline) (PMDA-ODA). Under electric field, both negatively charged MWCNTs and PMDA-ODA colloid particles migrate onto a positively charged anode simultaneously, and are converted to a coherent MWCNT/polyimide composite film in the ensuing imidization reaction. Uniform dispersion of MWCNTs in the composite film was observed using transmission electron microscopy. The thickness of the prepared composite film can be tuned by varying processing conditions such as deposition time and anode conductivity. The electrical conductivity of the composite film increased with increasing the concentration of MWCNTs in EPD suspension. The mechanical reinforcement of polyimide using MWCNTs was evaluated by tensile testing and nanoindentation testing.     

TiC改性炭石墨材料的微观结构与性能研究

研究了在炭石墨材料基料中均匀掺杂TiC陶瓷粉体，经高温烧结、原住合成反应、石墨化，制备了TiC改性炭石墨复合材料。研究了TiC改性炭石墨复合材料的微观结构，分析了TiC掺杂对炭石墨材料力学性能的影响，并从微观角度解释了TiC对炭石墨材料力学性能影响的机理。从研究结果可以看出，TiC掺杂可使炭陶瓷复合材料的抗折强度提高13．4％，抗压强度提高38．1％，气孔率降低16．9％；其机理在于TiC掺杂在炭陶瓷复合材料制备过程中能促进石墨化，使晶体更加完整、细化，有利于力学性能的提高。     

An alternate approach to synthesize TiC powder through thermal plasma processing of titania rich slag

This paper reports the preparation of fine titanium carbide (TiC) powder by using titania rich slag as a cheap raw material. The mixture of titania rich slag and activated charcoal was reacted in a thermal plasma reactor for 30 min under argon flowing atmosphere. The reaction product, a fused mass of Fe-TiC composite, was milled to fine powder at ambient atmosphere for 10 h then chemically leached for the removal of iron and other minor impurities. The obtained TiC powder after leaching was characterized by X-ray diffraction (XRD), Raman spectroscopy, electron probe micro analysis (EPMA), field emission scanning electron microscopy (FESEM) and particle size analysis (PSA). XRD, Raman spectroscopy results confirmed the formation of TiC. EPMA, EDS results indicated the synthesized product obtained after leaching to be free from iron and other minor impurities. Particle size analysis result revealed the average particle size of TiC powder to be 2.54 µm.     

High-Pressure Synthesis of Heat-Resistant Diamond Composite Using a Diamond-TiC0.6 Powder Mixture

The sintering behavior of synthetic diamond with a grain size of 2-4 µm was investigated at high pressure and high temperatures (6.5 GPa and 1600°-1900°C, respectively) in the presence of TiC_0.6 or TiC. No well-sintered diamond composite was synthesized from a diamond-TiC powder mixture under the examined conditions; however, a well-sintered diamond composite with a homogeneous microstructure was synthesized under the conditions of 6.5 GPa and temperatures >1800°C using a diamond-TiC_0.6 powder mixture. The diamond composite was hard (Vickers hardness of 45 GPa) and was composed of diamond and TiC, in which TiC was formed via the reaction of TiC_0.6 and carbon atoms of diamond. Neither graphitization nor cracking was observed in or on the composite after successive heat treatment at 900°-1400°C for 30 min each under vacuum. The Vickers hardness of the composite that was treated at 1500°C decreased to 40 GPa, whereas the Vickers hardness values for composites treated at temperatures of <1400°C were not changed. The present diamond composite is believed to be one of the most heat-resistant materials among the superhard composites and can be used as heat-resistant tools for superhard materials.     

硅化物-镍铁合金/碳化钛金属陶瓷的制备、组织结构与性能

研制了以熔融合金惰性气体雾化法制备的含有大量硅化物的镍铁合金粉末为烧结粘结相的硅化物-镍铁合金／碳化钛金属陶瓷。用SEM，EDS，XRD和热重天平等测试分析了金属陶瓷的组织结构与性能。结果表明：这种硅化物-镍铁合金／碳化钛金属陶瓷具有核／环形边缘结构，硅化物-镍铁合金对碳化钛粒子有较好的润湿烧结作用。研制的金属陶瓷的抗弯强度在1000～1200MPa，硬度HRA为80～90。由于合金中含有较高的对氧有较强亲和力的元素硅，在氧化过程中形成SiO2以及一系列复合氧化物构成的致密氧化膜，使合金具有高的抗高温氧化性能。     

Al2O3＋TiC陶瓷中Al2O3与TiC化学反应抑制的研究

本文通过Ｙ－盐溶液的形式加入到Ａｌ２Ｏ３粉料中,制备了Ｙ２Ｏ３表面固溶的Ａｌ２Ｏ３粉料,对其阻止Ａｌ２Ｏ３与ＴｉＣ之间的化学反应进行了研究。研究结果表明：采用Ｙ－盐溶液加入Ｙ２Ｏ３,Ｙ原子能均匀的分散在Ａｌ２Ｏ３的表面,高温时Ｙ２Ｏ３在Ａｌ２Ｏ３表面形成固溶体层,少量的Ｙ２Ｏ３加入量（０．３５ｗｔ％）,就能有效的阻止Ａｌ２Ｏ３与ＴｉＣ之间的化学反应。