TiC／Si3N4导电陶瓷复合材料的制备

通过气压烧结工艺制备了含１,５,２０,２５,３５ｗｔ％ＴｉＣ的Ｓｉ３Ｎ４陶瓷复合材料研究了其导电特性,该复合材料由充当绝缘体的Ｓｉ３Ｎ４和作为导电添加剂的ＴｉＣ组成,其电阻率主要取决于其中的ＴｉＣ含量。复合材料的渗流阈值ＶＣ为１６．４５－１８．５０ｖｏｌ％,当ＴｉＣ含量达到或超过该阈值时复合材料中就形成导电通路,电阻率迅速降低。     

电沉积Ni—Co合金及其结构研究

采用硫酸盐体系电沉积Ｎｉ－Ｃｏ合金，研究了电镀工艺参数对镀层组成及电流效率的影响，测定了镀层结构。实验发现：在Ｎｉ－Ｃｏ合金镀层中，当Ｃｏ含量低于７６ｗｔ％时，合金由两种面心立方结构的固溶体组成；Ｃｏ含量介于７６￣９０ｗｔ％之间时，由面心立方和六方密排两种结构的固溶体组成；Ｃｏ含量超过９０ｗｔ％时，合金只有一种立方密排结构的固溶体相成。     

电沉积Ni－Co合金及其结构研究

采用硫酸盐体系电沉积Ｎｉ－Ｃｏ合金，研究了电镀工艺参数对镀层组成及电流效率的影响，测定了镀层结构。实验发现：在Ｎｉ－Ｃｏ合金镀层中，当Ｃｏ含量低于７６ｗｔ％时，合金由两种面心立方结构的固溶体组成；Ｃｏ含量介于７６～９０ｗｔ％之间时，由面心立方和六方密排两种结构的固溶体组成；Ｃｏ含量超过９０ｗｔ％时，合金只由一种六方密排结构的固溶体相成。     

Sn-Bi合金电镀

概述了含有Ｓｎ２＋、Ｂｉ３＋和多元羧酸及其盐等组成的Ｓｎ－Ｂｉ合金电镀工艺,可以获得０．１ｗｔ％～７５ｗｔ％Ｂｉ的Ｓｎ－Ｂｉ合金镀层,适用于陶瓷、塑料、铅玻璃和铁氧体等复合金属物品。     

低分子聚碳硅烷制备Si-C-N复合超细微粉

以高碳低分子聚碳硅烷（ＬＰＳ）为原料,利用其原料的特点,采用气相反应热裂解方法制备出Ｓｉ－Ｃ－Ｎ复合微粉,系统地讨论了合成工艺条件对采用富碳有机硅原料制备含Ｎ的Ｓｉ－Ｃ－Ｎ复合微粉产物的性质以及形貌、组成,尤其是微粉中Ｎ含量等的影响,并较详细地探讨了ＮＨ３与ＬＰＳ分解反应的过程及与ＬＰＳ制备ＳｉＣ微粉的反应过程的差别。所合成的无定形Ｓｉ－Ｃ－Ｎ复合微粉;粒径３０－５０ｎｍ,球碳（质量分数,下同）１     

巴基管/纳米SiC陶瓷材料的研究

本文研究了巴基管／纳米ＳｉＣ陶瓷材料。初步讨论了在热压条件下,巴基管、烧结温度和添加剂对其机械性能的影响。结果表明,添加了巴基管后,纳米ＳｉＣ的抗弯强度（室温）和断裂韧性有所提高。优化的工艺方案是在ＳｉＣ中添加１０ｗｔ％的巴基管、１ｗｔ％的Ｂ４Ｃ,烧结温度２０００℃（保温１ｈ,压力２５ＭＰａ）;其性能达到：相对密度９４．７％、抗弯强度（室温）３２１．２２ＭＰａ、断裂韧性３．８２ＭＰａ·ｍ＾１／２。     

纳米Si3N4-SiC(Y2O3)复合粉末的氨解溶胶-凝胶法合成

以硅溶胶、尿素和碳黑为原料,经氨解溶胶－凝胶、碳热还原法合成了纳米Ｓｉ３ｎ４－ＳｉＣ复合粉末。通过在硅溶胶中引入Ｙ（ＮＯ３）３,合成了Ｓｉ３ｎ４－ＳｉＣ－Ｙ２Ｏ３超细复合粉末,Ｙ２Ｏ３的加入有助于降低Ｓｉ３Ｎ４－ＳｉＣ的合成温度。采用ＸＰＳ和ＸＲＤ分析复合粉末中Ｙ的存在状态表明：一部分Ｙ固溶在Ｓｉ３Ｎ４－ＳｉＣ中,加有一部分以Ｙ２Ｏ３形式存在,Ｓｉ３Ｎ４－ＳｉＣ－Ｙ２Ｏ３复合粉末的烧结性能良好。     

炉渣微晶玻璃核化机理的研究

采用ＤＴＡ、ＳＴＥＭ、ＥＤＡＸ、ＳＡＥＤ和ＸＲＤ等测试方法，研究了炉用量对ＣａＯ－Ａｌ２Ｏ３－ＳｉＯ２系统玻璃核化析晶的影响作用，结果表明，在不引入其它核剂的情况下，随着炉渣用量的增加，玻璃的整体析晶程度增强，当炉渣含量为玻璃组成的４０ｗｔ％以上时，炉渣中所含的硫（Ｓ＾２－）能有效地促进玻璃的微晶化，选择适当的炉渣用量和热处理温度可获得性能优良的微晶玻璃材料。     

ZnS：Cu，Co，Gd，Er发光体线膨胀系数因子的研究

在ＺｎＳ：Ｃｕ．Ｃｏ．Ｇｄ．Ｅｒ发光体与同种基础釉组成的发光釉中，选择发光体含量分别为１５ｗｔ％，２０ｗｔ％和２５ｗｔ％的３种发光融为试样，测定了它们的线膨胀系数。把这些线膨胀系数对发光体的含量进行了线性回归，得出了线膨胀系数、发光体含量和基础釉含量三者之间的函数关系式．此函数关系式表明：在发光釉中．随着发光体含量的增加，发光釉的线膨胀系数降低．这种发光体的线膨胀系数因子为０．５５×１０（－７）Ｃ（－１）。     

壳聚糖／醋酸纤维素渗透汽化共混膜的研究Ⅰ．膜的制备及其渗透汽化性能

本文以壳聚糖（ＣＳ）和醋酸纤维素（ＣＡ）为膜材料，研究了ＣＳＣＡ渗透汽化共混膜的制膜条件，分析了该膜的渗透汽化性能及影响因素。结果表明：ＣＳＣＡ共混膜对乙醇－水混合液具有良好的渗透汽化分离性能，适合分离浓度为５０ｗｔ％～９０ｗｔ％的乙醇水溶液     

铝元素对锌镀层耐蚀性的影响

研究了用复合电沉积法制备的锌铝镀层在微酸性腐蚀介质中的耐蚀性。试验结果证明,氢氧化铝也能改善镀层的耐蚀性,但不如铝粉的作用显著。EPMA和ICP显示含氢氧化铝和含铝粉镀层中的铝呈均匀分布状态,但前者铝的含量为50ppm,后者为0.15wt％。x-射线衍射法揭示溶液中的氢氧化铝能使镀层的结晶细致,晶面择优取向程度增加。当镀液中含有铝粉时,所得镀层的结晶晶面的择优程度更大,结构则成为层状的。因此,氢氧化铝和铝粉是通过提高镀层的晶面择优取向程度,从而改善了其耐蚀性能。     

Electrical conductivity and infrared radiation performance of SiC-CNT composite ceramics

SiC ceramic is an excellent infrared source material that can be used in a wide range of fields, like infrared heating, night vision and communication, but its poor electrical properties limit it. In this work, carbon nanotubes (CNTs) were selected as conductive phase filler, and SiC-CNT composite ceramics were prepared by SPS method. The effects of CNT content on the microstructures, electrical properties and infrared radiation performance of the composites were studied. The introduction of CNT effectively reduced the height of Schottky barrier at grain boundary, thus weakening the grain boundary effect, reducing the grain boundary resistance, further weakening the nonlinear characteristics and bulk resistivity of the composite ceramics. When the content of CNT was 1 wt%, electrical percolation was achieved, and the bulk resistivity of SiC ceramics dropped by nearly 3 orders of magnitude. The preferred orientation distribution of CNT made the bulk resistivity perpendicular to the pressure direction R_⊥ always lower than that parallel to the pressure direction R_//. The sample with 5 wt% CNT assumed linear conductivity characteristics, with bulk resistivity in different direction of 16.5 Ω cm (R_//) and 11.8 Ω cm (R_⊥), respectively. CNT addition slightly increased the infrared radiation performance of SiC ceramics, and the sample with 5 wt% CNT possessed the highest total emissivity of 0.675. The excellent electrical conductivity and infrared radiation performance of SiC-CNT composite ceramic confirmed this class as a promising infrared source material.     

炭／炭复合材料SiC／Mo（Six，Al1-x）2涂层形成机理与抗高温氧化性能

采用高温包渗技术在炭／炭复合材料表面制备了SiC／Mo（Six,Al1-x）2复合涂层,采用两步反应法研究了复合涂层的生成机理。发现复合涂层是由Si、Al2O3、SiC、MoSi2原始粉末材料与基体炭材料经过复杂化学反应生成的SiC、Mo（SixAl1-x）2以及微量Mo4．8Si3C0．6固溶体组成。在较低温度下（〈1750℃）,单质硅与基体碳的液-固相反应,经过2小时后可以在炭／炭复合材料表面和内部孔隙表面生成致密的SiC过渡涂层;在较高温度下（≤2000℃）,SiC、Al2O3和MoSi2间的反应较为复杂,其主要过程为SiC与Al2O3间生成液体硅、液体铝和气态SiO、Al2O的多相反应,该反应生成的液体铝能够与MoSi2颗粒发生置换反应,生成熔点降低的Mo（Six,Al1-x）2转移涂层;同时,生成的液体硅与CO反应生成晶须状β—SiC,并与Mo（Six,Al1-x）2形成增强型复合涂层。本文还研究了过量单质Si和SiC对Mo（Six,Al1-x）2的还原反应,化学反应推论与实验结果相吻合。以新提出的涂层生成机理为指导,以粉末原料质量组成为Si10％,Al2O3 10％,SiC54％和MoSi226％时所制得了致密并且无粘结的复合涂层材料,并研究了封孔处理后复合材料的抗氧化性能。     

锌-碳化硅复合镀层的制备及性能

以钢板为基体,在普通氯化物镀锌液中加入碳化硅制得Zn-SiC 复合镀层。研究了电流密度、温度以及 SiC、氯化铵的质量浓度对镀层耐蚀性和显微硬度的影响,得到制备 Zn-SiC 复合镀层的较佳工艺条件:电流密度 0.5～1.0 A/dm2,温度 20～25℃,SiC 10～11 g/L,氯化铵 250～260 g/L。在较佳工艺下,Zn-SiC 复合镀层中 SiC 的质量分数为 0.75%,耐蚀性优于纯锌镀层,镀层中 SiC 的存在有利于生成晶粒细小、致密且显微硬度较高的镀层。     

两种Cu包裹SiC颗粒复合粉体工艺的研究

为改善SiC与金属的结合性，分别采用化学镀法和非均相沉淀法制备Cu包裹SiC颗粒复合粉体。通过XRD衍射分析得出以上两种包裹方法都可以得到大部分包裹着Cu相的SiC颗粒，同一组分比例下非均相沉淀法得到的Cu相对于化学镀法得到的Cu多，且非均相沉淀法同样得到相对较多的Cu2O。SEM形貌观察分析得出：化学镀法容易制备Cu包裹粒径较大碳化硅颗粒，非均相沉淀法容易制备Cu包裹粒径较大碳化硅颗粒，其大小、形状均对包覆效果有影响，小颗粒的碳化硅颗粒比大颗粒的包覆效果好，球形颗粒比其他形貌的颗粒包覆效果好。     

碳纤维增强碳复合材料表面多层复合涂层中SiC和TiC内层的比较(英文)

采用包埋法制备了碳纤维增强碳(carbon fiber reinforced carb on composites,C/C)复合材料表面多层涂层,包括SiC,TiC内层,SiC,TiC中间层以及SiC+TiC复合外层。利用场发射扫描电镜和X射线衍射对其表面和断面的结构进行研究。结果显示:和TiC内层相比较,SiC内层较厚而且致密,具多孔结构且和C/C复合材料结合紧密;TiC内层较薄且和C/C复合材料结合松散。制备的SiC+TiC复合外层由SiC,TiC和Ti3SiC2组成。     

Cu包裹SiC复合粉体工艺的研究

选用工业生产的SiC粉,利用非均相沉淀法,将Cu均匀地包裹在SiC表面,得到了包裹均匀的Cu／SiC复合粉体。通过调节反应溶液的pH值控制SiC颗粒表面的zeta电位,解决包覆过程中颗粒团聚的问题。X射线衍射分析表明：经过包覆反应能够得到大部分包裹着Cu相的SiC颗粒。SEM形貌观察分析表明：SiC颗粒的大小、形状均对包覆效果有影响,小的SiC颗粒比大的包覆效果好,球形颗粒比其他形貌的包覆效果好。     

Ni包裹SiC对SiC(Ni)/Fe复合材料性能的影响

分别以SiC粉体和Ni包裹的SiC复合粉体为硬质相,采用热压工艺(1000°C,20°C/min,40 MPa和45 min)制备了SiC含量为1 wt%~9 wt%的SiC/Fe复合材料。采用扫描电镜(SEM)、能谱仪(EDS)和X射线衍射仪(XRD)等研究了复合材料的界面反应物。研究结果表明:Ni过渡层的存在有效避免了SiC颗粒与Fe基体之间的化学反应。随着Ni包裹SiC粉体含量的增加,复合材料的相对密度和抗弯强度先增加后减小,当SiC(Ni)粉体含量为5 wt%时达到最大值。     

Microstructural and compositional characterisation of the pyrocarbon interlayer in SiC coated low density carbon/carbon composites

SiC coated carbon bonded carbon fibre (CBCF) composites, a special class of carbon/carbon composites for thermal insulation, were investigated. Successful deposition of SiC requires the CBCF material to be first given a pyrocarbon coating. SiC coating on pyrocarbon coated CBCF was assessed using several analytical techniques. X-ray diffraction identified the coating as β SiC. The fibre orientation in two perpendicular planes was determined using X-ray microtomography, and it was found to be random in one plane whereas there was a preferred orientation in the other plane. A comparison was made between the uncoated and pyrocarbon coated substrates in terms of surface roughness, purity and crystallinity, using white light interferometry, neutron activation analysis/secondary ion mass spectrometry and transmission electron microscopy, respectively. The higher roughness, greater purity and increased levels of crystallinity of pyrocarbon coated CBCF are considered to be responsible for the successful deposition of a SiC coating on this material.     

Laser additive manufacturing and homogeneous densification of complicated shape SiC ceramic parts

To improve the density of SiC ceramic components with complicated shape built by laser sintering (LS), cold isostatic pressing (CIP) and reaction sintering (RS) were incorporated into the process. In the process of LS/CIP/RS, Phenol formaldehyde resin (PF)-SiC composite powder was prepared by mechanical mixing and cold coating methods, with an optimized content of PF at 18?wt%. For the purpose of obtaining improved density of the sintered body after final reaction sintering, carbon black was added into the initial mixed powder. The material preparation, LS forming and densification steps were optimized throughout the whole fabrication process. The final sintered SiC bodies with the bending strength of 292 ~ 348?MPa and the density of 2.94–2.98?g?cm^{? 3} were prepared using the PF coated SiC-C composite powder and the LS / CIP / RS process. The study further showed a positive and practical approach to fabricate SiC ceramic parts with complicated shape using additive manufacturing technology.