Reaction Engineering Aspects of Manufacturing of Finite Inorganic Fibers

有限无机纤维制造的反应工程方面

• 批准号: 8813918
• 负责人: Vladimir Hlavacek
• 金额: $ 26.83万
• 依托单位: SUNY at Buffalo
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-12-01 至 1992-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8813918&HistoricalAwards=false
• 关键词: Reaction; Engineering; Aspects; Manufacturing; Finite

Ceramics are valuable because they can withstand heat and chemical attack. They have a critical drawback--they are brittle, do not deform under load and therefore crack or break easily. Flaws in their structure cause this cracking, therefore much effort in ceramic research is aimed at developing new processing techniques that minimize microscopic flaws. When the material is produced in the form of fine fibers, the brittleness properties are greatly improved because the probability that a sample of material will contain a flaw large enough to cause brittle failure deceases as the sample size is reduced. Also, if one fiber in a bundle fails, the crack cannot propagate further and the other fibers remain intact. Composites harness the fiber's attractive properties and eliminate their drawbacks by imbedding them in the matrix of another material. For use in high temperature applications, these fibers are often imbedded in metal matrices along with the temperature resistance, reinforcing fiber and the metal's ductility lends added usefulness to the composite. Light metals--aluminum, magnesium and titanium--are common matrices. Silicon carbide (SiC) fibers are promising for reinforcing because of their high intrinsic strength, stiffness, high temperature stability, and excellent oxidation resistance. Boron carbide (B4C), titanium-diboride (TiB2), titanium carbide (TiC), and titanium bromide (TiB) fibers also have potential to use chemical vapor deposition (CVD) to manufacture SiC, B4C, TiC and TiB fibers. The CVD process involves the information of a solid by a heated substrate. Typically, a small-diameter substrate wire is run through a glass reaction tube, and suitable gases are introduced. The substrate is resistance heated causing the gas to react and deposit in the heating wore. A key problem of efficient manufacturing batch to continuous flow systems, scale-up of the laboratory continuous system to a pilot plant unit, modeling and simulation of the CVD reactions and securing cheap sources of precursors necessary for the CVD process. The PI will do both experimental and modeling work to study the effect of: (1) Pretreatment of the substrate fiber by hydrogen, steam and nitric acid on deposition rate, strength, toughness and adhesivity. (2) The purity of the material on the mechanical quality of the fiber. (3) Gas flow rate on the rate of deposition. (4) Hydrogen to silane ratio and temperature on the formation of stoichiometric SiC. (5) BC13, hydrocarbon (CH4/CC14) and H2 concentrations on the deposition of B4C. (6) The ratio of C to Ti fed for production of TiC. Detailed kinetic study experiments will be carried out in a batch reactor to determine kinetic parameters such as reaction control regimes, activation energy, etc. This will be used in the design of the larger scale continuous units.

陶瓷很有价值，因为它们可以承受热量和化学侵蚀。它们有一个严重的缺点——它们很脆，在负载下不会变形，因此很容易破裂或断裂。 其结构缺陷会导致这种裂纹，因此陶瓷研究的大量努力旨在开发新的加工技术，以最大限度地减少微观缺陷。 当材料以细纤维的形式生产时，脆性特性得到极大改善，因为随着样品尺寸的减小，材料样品中包含足够大以导致脆性破坏的缺陷的可能性降低。 此外，如果一束纤维中的一根纤维失效，裂纹就无法进一步传播，而其他纤维则保持完整。 复合材料利用纤维的吸引人的特性，并通过将其嵌入另一种材料的基体中来消除其缺点。 对于高温应用，这些纤维通常嵌入金属基体中，同时耐温性、增强纤维和金属的延展性为复合材料增加了实用性。 轻金属——铝、镁和钛——是常见的基质。 碳化硅（SiC）纤维因其高固有强度、刚度、高温稳定性和优异的抗氧化性而有望用于增强材料。 碳化硼 (B4C)、二硼化钛 (TiB2)、碳化钛 (TiC) 和溴化钛 (TiB) 纤维也有潜力使用化学气相沉积 (CVD) 来制造 SiC、B4C、TiC 和 TiB 纤维。 CVD 工艺涉及通过加热基材获取固体信息。 通常，小直径基底线穿过玻璃反应管，并引入合适的气体。 基材被电阻加热，导致气体发生反应并沉积在加热磨损中。 高效制造批量到连续流动系统、将实验室连续系统放大到中试工厂单元、CVD 反应的建模和模拟以及确保 CVD 过程所需的廉价前体来源的关键问题。 PI将进行实验和建模工作来研究以下方面的影响：（1）用氢气、蒸汽和硝酸预处理基材纤维对沉积速率、强度、韧性和粘附性的影响。 (2)材料纯度对纤维机械质量的影响。 (3)气体流量对沉积速率的影响。 (4)氢与硅烷的比例和温度对化学计量SiC形成的影响。 (5)BC13、碳氢化合物(CH4/CC14)和H2浓度对B4C沉积的影响。 (6)用于生产TiC的C与Ti的比率。 详细的动力学研究实验将在间歇式反应器中进行，以确定反应控制方式、活化能等动力学参数。这将用于更大规模的连续装置的设计。