Silicon assistant carbothermal reduction for SiC powders

The silicon assistant method to increase the reaction yield of carbothermal reduction of silica at a lower temperature is reported. The effect of silicon on the carbothermal reduction process has been investigated in detail. Compared with traditional reduction, the introduction of silicon can change the reaction path and further increase the conversion of silicon carbide at a lower temperature. It is considered that the assistant reduction consists of three steps: vaporizing and melting of silicon, formation of silicon monoxide, and synthesis of silicon carbide. The morphology of the synthesized SiC powders through the silicon assistant method can be affected apparently by the experimental temperature.     

Surface Modification of Silicon Carbide Powders with Aminoorganosilanes

To study the surface modification of SiC powders with aminoorganosilanes, high solid loading and low viscosity SiC slurry was prepared. Three kinds of aminoorganosilanes were used in the experiment. Infrared Fourier transform spectrometry （Nicolet20SX, America） was applied to analyze the surface characterization of modified SiC powders. The largest solid loading of SiC coated with WD-52 slurry had increased to 54.5vo1% and the stabilization also increased remarkably. At the same time, the viscosity of SiC slurry declined. Comparing with WD-50 and WD-57, WD-52 is most effective for modification of SiC powders.     

CVD法快速制备SiC过程分析

采用TMS（CH3SiCl3)为原料,H2为载气,Ar为稀释气,在1000－1200℃范围以内以石墨为基体,通过化学气相沉积法（CVD）制备地SiC块体材料,在特定的工艺条件下,SiC的生长速率可达0．6mm/h,结合实验结果,研究了常压SiC-CVD过程中,对SiC生长速率产生影响的若干因素的作用,初步探索了基体尺寸与沉积室尺寸的比例、沉积温度、稀释气流量以及沉积时间对沉积速率的影响,综合分析提高了SiC生长速率的原因。     

Thermal oxidation of SiAlON powders synthesized from coal gangue

The oxidation behavior of different SiAlON phases(β-SiAlON,X-phase SiAlON and 12H powders) synthesized from coal gangue in air atmosphere was investigated using isothermal thermogravimetry(TG) and field-emission scanning electron microscopy(FE-SEM).The effect of ferric oxide impurities in coal gangue was studied.The results show that ferric oxide contributes to the growth of SiAlON crystalline during the synthesis process.In the oxidation experiment,the existence of ferric oxide decreases the oxidation resi...     

不同粒径碳化硅粉体的复合烧结与表征

以氮化硅为烧结助剂,聚乙烯吡咯烷酮（PVP）为黏结剂,通过重结晶烧结法制备了纯碳化硅（SiC）陶瓷。采用X射线衍射、扫描电子显微镜和阿基米德定律对产物的结构、形貌和相对密度进行了表征,主要研究了SiC细粉的质量分数对SiC晶粒形貌的影响。结果表明,SiC细粉质量分数的变化对烧结样品的晶粒尺寸与形貌及其相对密度有较大影响。细粉质量分数由0%增加至60%,SiC晶粒的形貌由等轴状晶粒过渡为六方片状晶粒,晶粒尺寸非线性增加,样品的相对密度则呈先增加后降低的趋势,当细粉的质量分数为40%时,SiC陶瓷的相对密度最高。因SiC高温（2 000 ℃以上）蒸发与凝聚的烧结作用,当SiC细粉的质量分数为60%时,重结晶普遍发生,且SiC粗粉晶粒尺寸急剧增大,形成六方片状。     

Synthesis of Ti3SiC2/TiB2 Composite by In-situ Hot Pressing (HP) Method

Ti3SiC2/TiB2 composite was successfully obtained by hot pressing Ti/TiC/Si/B4C power mixtures.Volume fraction of TiB2 in Ti3SiC2/TiB2 composite can not exceed 10%.Incorporation of excessive TiB2 will affect the reactions process.TiC and Ti5Si3 were two important intermediate phases during the whole reactions.The microstructure characteristics of the Ti3SiC2/TiB2 composites were analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).The experimental results show that the grains of Ti3SiC2/TiB2 composite are structured in a layered form,and the formation of TiB2 particles as reinforcements with elongated or equiaxed shape distributes in Ti3SiC2 matrix.     

碳化硅异质外延薄膜生长及表面缺陷研究

讨论了引入Ⅲ-V族氮化物为蓝宝石与碳化硅中间的缓冲层，用常压气相外延手段在蓝宝石/Ⅲ-V族氮化物复合衬底上异质外延碳化硅薄膜的过程，在C面（0001）蓝宝石上成功地生长出Sic薄膜，扫描电子显微镜显示薄膜表面连续，光滑，证明良好的氮化物缓冲层对碳化硅薄膜异质生长具有重要的意义，同时在表面发现直径为1-10μm的六角形缺陷，对缺陷面密度与工艺参数的关系进行了分析，并对缺陷产生的机理进行了探讨，认为反应产生物的腐蚀是产生六角形缺陷的来源。     

化学复合镀Ni—P—SiC的研究

研究了在Ni-P化学镀液中添加分散剂A及SiC微粒，得到的化学镀Ni-P-SiC复合镀层，并研究了Ni-P-SiC化学共沉积工艺及其镀层性能，结果表明，该复合镀层附着性好，经一定温度热处理后，具有较高的硬度及良好的耐磨性。     

SiC欧姆接触特性

通过离子注入外延层实现高浓度掺杂和直接采用高掺杂外延层两种方法分别制备了4H-SiC欧姆接触,对应退火条件分别为(950℃,Ar,30 min)和(1000℃,N2,2 min).采用传输线法测试得到的比接触电阻分别为1.359×10-5Ω.cm2和3.44×10-6Ω.cm2.二次离子质谱分析表明,高温退火过程中镍硅化合物和TiC的形成有利于欧姆接触特性.     

应用TLC法鉴定卵磷脂纯度

对薄层层析法在卵磷脂产品纯度分析中的应用进行了初步的探讨 .试验结果表明 ,该方法快速、简单、直观、准确 ,在生产及科研过程中较为实用 .     

Chemical vapor deposition of SiC at different molar ratios of hydrogen to methyltrichlorosilane

Chemical vapor deposition (CVD) of SiC from methyltrichlorosilane (MTS) was studied at two different molar ratios of H₂ to MTS (n(H₂)/n(MTS)). The total pressure was kept as 100 kPa and the temperature was varied from 850 to 1 100 °C at a total residence time of 1 s. Steady-state deposition rates as functions of reactor length and of temperature, investigated at different n(H₂)/n(MTS) values, show that hydrogen exhibits strongly influences on the deposition rate. Especially, the deposition of Si co-deposit can be obtained in broader substrate length and at higher temperatures with increasing hydrogen partial pressure. Influence of hydrogen on the deposition process was also studied using gas phase composition and deposit composition analysis at various n(H₂)/n(MTS). SEM micrographs directly show the variation of surface morphologies at various n(H₂)/n(MTS). It can be found that the crystal grain of the deposit at 1 100 °C is better developed and the crystallization is also improved with increasing n(H₂)/n(MTS).     

碳化硅添加剂对紫色页岩陶粒烧胀性的影响

利用碳化硅为膨胀成份,紫色页岩为主要原料制作陶粒,研究碳化硅掺加量和焙烧温度对紫色页岩烧胀性的影响,探讨碳化硅引起紫色页岩陶粒膨胀的机理。试验结果表明外加碳化硅0.3wt%可使紫色页岩在1 120℃时膨胀;当碳化硅掺加量提高时,紫色页岩起始烧胀温度下降,添加量为1.2wt%时,起始烧胀温度为1 100℃。     

TiB_2/SiC陶瓷复合材料制备工艺的研究

以TiO2、B4C和C为原料,基于原位合成法在SiC基体中生成TiB2颗粒,并采用无压烧结法制备出TiB2/SiC复合陶瓷.通过对复合材料制备工艺的研究,发现：高于1 300℃的预烧结能形成TiB2/SiC复合陶瓷坯体.C含量、烧结温度和保温时间对复合材料的相对密度均有影响.当C含量（质量分数）为4%时、在1 400℃×60 min＋2000℃×30 min的烧结工艺下能够制备出致密的TiB2/SiC陶瓷复合材料.微米级TiO2粉比纳米级TiO2粉更有利于形成较致密的烧结复合材料.随着生成TiB2体积分数的增加（5%～20%）,复合材料中TiB2颗粒逐渐粗化,间距逐渐变小.对复合材料的烧结机理还进行了分析.     

Sol-Gel法制备纳米二氧化钛粉体

以钛酸四丁酯为原料，采用溶胶-凝胶法(Sol-Gel)制备出了晶粒尺寸6～23nm的二氧化钛粉体，并对酸度．制备温度和升温速率等条件进行了研究．实验证明：室温下，硝酸与钛酸酯摩尔比为0．30～0．39；450℃左右煅烧2h可得锐钛型二氧化钛纳米粉体；600℃煅烧2h得到金红石型二氧化钛粉体。     

化学镀法制备钴包覆碳化硅复合粉末的研究

采用化学镀法制备钴包覆碳化硅复合粉末,通过研究化学镀过程中钴盐浓度、还原剂浓度、络合剂浓度、缓冲剂浓度、温度以及pH值等因素对沉积速率的影响规律,得到化学镀钴的优化条件。利用XRD、SEM和EDAX等测试手段对该复合粉末的组分及形貌进行了表征。实验和表征结果表明,当硫酸钴浓度为30～50g/L,次磷酸钠浓度为40g/L,柠檬酸钠浓度为60～70g/L,控制温度为50～70℃以及调节pH值等于8时,镀层沉积速度较快,所得粉体表面被钴均匀包覆。     

碳化硅（SiC）器件制造工艺中的干法刻蚀技术

简述了在ＳｉＣ材料半导体器件制造工艺中,对ＳｉＣ材料采用干法刻蚀工艺的必要性．总结了近年来ＳｉＣ干法刻蚀技术的工艺发展状况．     

SiCp／Al复合材料的压铸法制造工艺的研究

采用先制预制块然后加压铸造的方法制得了致密均匀的ＳｉＣｐ／Ａｌ复全材料，与基体铝合金相比，其屈服强度提高４６％，抗拉强度提高２４％，弹性模量提高８７％。     

SiC微粒填充铸型尼龙复合材料的研究

对SiC微粒填充铸型尼龙（MC尼龙）复合材料进行了研究,试验结果表明：材料制备的工艺流程对其力学性能有明显的影响,使用钛酸酯偶联剂对颗粒进行表面处理比硅烷偶联剂（KH550）更有效。随着填料含量的变化材料的力学性能发生变化,填料质量分数大约在5％时具有最好的综合性能。