CVD法制备陶瓷材料的进展

本文简单介绍了ＣＶＤ的基本原理，评述了ＣＶＤ在制备超细粉、高纯致密涂层／薄膜、高熔点高强度高模量陶瓷纤维／晶须、体陶瓷等方面的应用。     

先进陶瓷材料制备研究进展

先进陶瓷材料具有高强度、高硬度、耐高温、耐腐蚀等优点,现已成为材料科学工作者研究关注的热点。本文概述了行业中具有前景的陶瓷素坯制备方法、烧结技术、先进陶瓷精细加工技术,分析了每种技术方法各自的优点,并对先进陶瓷材料制备技术的研究重点和发展趋势进行了总结。     

先进结构陶瓷材料的研究进展

先进陶瓷材料因其具有高熔点、高强度、高硬度、耐磨损、抗腐蚀和抗氧化等优良特性,在许多应用领域有着金属等其它材料不可替代的地位。本文综述了先进结构陶瓷材料的研究应用现状和发展趋势。     

先进铁电压电陶瓷材料

先进功能陶瓷是包括具有声、光、电、力、热、磁等不同性能及其交叉偶合效应的压电、磁电、热电、光电等能量互换的功能材料,主要包括铁电压电陶瓷、微波介质陶瓷、半导体敏感陶瓷、磁性陶瓷等.因此,先进功能陶瓷材料当前已被广泛应用于电子信息、航空航天、生物医疗、储能等领域.     

化学气相沉积法制备单壁碳纳米管研究进展

单壁碳纳米管的独特性能使其成为一种有着极大应用前景的新兴纳米材料,本文主要介绍了催化剂、裂解温度、载气等因素对化学气相沉积法（CVD）制备单壁碳纳米管的影响和采用化学气相沉积制备定向单壁碳纳米管方面的研究进展情况。     

先进陶瓷材料研究现状

综述了先进的研究现状，介绍了目前先进陶瓷的主要材料，应用与市场情况以及制备工程中的材料设计。本文还简要评了我国自50年代来在先进陶瓷研究领域的进展，并展望了先进陶瓷的研究开发趋势。     

化学气相沉积法制备高质量石墨烯方法研究与展望

石墨烯自发现以来因其杰出的理化性能广受关注,制备石墨烯的方法层出不穷.目前,采用化学气相沉积(CVD)技术实现了规模化制备高质量石墨烯.但石墨烯在制备过程中依然遇到了一些的瓶颈,如石墨烯产品污染、破损、皱褶,尤其是在高温条件下制备石墨烯成本较高等.根据近年来石墨烯制备技术和方案进行分析,总结整理近年来关于CVD制备高质...     

论化学气相沉积(CVD)金刚石技术最新发展

描述了国内外化学气相沉积(CVD)金刚石技术研究及产业最新进展,介绍了CVD金刚石的基本生产方法、加工手段、产品类型及应用领域。通过对国内外CVD金刚石技术及产品研究最新进展情况的介绍,指出了我国与世界先进的(CVD)金刚石技术存在的差距,阐述了CVD金刚石市场发展存在的问题并提出改进的建议。     

化学气相沉积法合成纳米碳管阵列研究

研究以环己烷为前驱体采用化学气相沉积法制备纳米碳管阵列。将催化剂二茂铁定量溶解在环己烷中，通过载气夹带进入反应器中，采用化学气相沉积方法定向生长出炭纳米管阵列，此法有效地控制反应体系中的催化剂含量，使生产稳定性及重现性较好。并通过透射电子显微镜、扫描电子显微镜、拉曼光谱及X射线衍射对产品形态和结构进行分析和表征，所制备出的纳米碳管阵列形态比较规整，纯度较高，具有较好的石墨微晶结构；并对纳米碳管的生长机理进行了详细讨论。     

CVD法制备硅硼碳氮陶瓷的化学反应热力学研究

本文针对制备SiBCN陶瓷所用的SiCl_3CH_3–BCl_3–NH_3–H_2体系,基于已建立的热化学数据库,根据化学平衡原理,确定了不同工艺参数下各反应体系中一些重要产物的平衡产量分布,给出了相应体系的固相产物分布规律,为实验研究提供可靠的理论参考。     

Advanced ceramics and coatings for erosion-related applications in mineral and oil and gas production: A technical review

The applications of advanced ceramics, composites and coatings in mineral, mining, fuel production, and processing are reviewed. The materials include oxide and non-oxide ceramics (specifically SiC-based), ceramic–ceramic, and ceramic–metal composites, coatings on metallic components where functional application properties can be achieved. Some principles of materials selection, specifically for erosion wear and corrosion applications, and manufacturing are considered. The examples of the successful development and processing of ceramics, coatings, and composites with manageable structures and phase compositions, in the erosion-related applications, particularly conducted by the author, are discussed and reviewed. Specifically, industrially employed types of ceramics and processing routes were focused on the considered applications. Particular demands for advanced materials with high reliability and complex shapes or for protective coatings on complex shape steel components and long tubing with inner surface protection require novel and optimized processing. The factors affecting erosion and erosion–corrosion resistance and the paths for the erosion resistance enhancement of ceramic and coating materials are considered. Ceramic components design, technology, and installation features are reviewed.     

Zeolite ceramics with ordered microporous structure and high crystallinity prepared by cold sintering process

4A [Na₉₆(Al₉₆Si₉₆O₃₈₄)⋅216H₂O] and 13X [Na₂(Al₂Si_3.3O_10.6)⋅7H₂O] zeolite ceramics were prepared by cold sintering processes, and the physical properties were investigated together with the structure characterization. There were four primary parameters controlling the preparation process: content of NaOH, pressure, temperature, and holding time. Zeolite ceramics with the idea ordered microporous structure and high crystallinity were obtained at 393 K under 450~550 MPa with a holding time of 5 min from the solution with 20 wt% NaOH. A high compressive strength up to 60 MPa and low Young's modulus down to 76 MPa were achieved in 13X zeolite ceramics, and the present ceramics might provide potential applications in damping materials and thermal insulating materials.     

Adhesion properties of CVD diamond film on binder-less sintered tungsten carbide prepared by the spark sintering process

This paper describes the adhesion property of chemical-vapor-deposited (CVD) diamond film on tungsten carbide (WC) bodies prepared by spark sintering without a binder. WC bodies ranging from 70 to 95% of density ratio have been sintered under different sintering conditions, and their mechanical properties, such as hardness and bending strength, have been measured. High-quality diamond films with a higher nucleation density compared to that on WC–Co have been deposited on this WC substrate using the microwave plasma CVD method. A comparison study using indentation tests shows that the adhesive strength of diamond films on this binder-less sintered WC is remarkably superior to that on WC–Co, which is believed to result from the increase in diamond nucleation density, the enhanced mechanical bonding between the substrate and the diamond film and the well-matching of thermal expansion coefficients caused by the absence of the fatal obstacle of cobalt. Moreover, an increase in adhesive strength has occurred on the binder-less sintered WC with lower density ratios.     

Moisture barrier properties of thin organic-inorganic multilayers prepared by plasma-enhanced ALD and CVD in one reactor

A widely used application of the atomic layer deposition (ALD) and chemical vapour deposition (CVD) methods is the preparation of permeation barrier layers against water vapour. Especially in the field of organic electronics, these films are highly demanded as such devices are very sensitive to moisture and oxygen. In this work, multilayers of aluminium oxide (AlO _x ) and plasma polymer (PP) were coated on polyethylene naphthalate substrates by plasma-enhanced ALD and plasma-enhanced CVD at 80℃ in the same reactor, respectively. As precursor, trimethylaluminium was used together with oxygen radicals in order to prepare AlO _x , and benzene served as precursor to deposit the PP. This hybrid structure allows the decoupling of defects between the single AlO _x layers and extends the permeation path for water molecules towards the entire barrier film. Furthermore, the combination of two plasma techniques in a single reactor system enables short process times without vacuum breaks. Single aluminium oxide films by plasma-enhanced ALD were compared to thermally grown layers and showed a significantly better barrier performance. The water vapour transmission rate (WVTR) was determined by means of electrical calcium tests. For a multilayer with 3.5 dyads of 25-nm AlO _x and 125-nm PP, a WVTR of 1.2 × 10 ⁻³ gm⁻²d⁻¹ at 60℃ and 90% relative humidity could be observed.     

Cellular silica-based ceramics prepared by direct foaming at high temperature

Cellular silica-based ceramics, including Si₃N₄/SiO₂ composite ceramics and monolithic silica ceramics, with dense shell and closed cells with dense and crack-free cell wall inside was prepared by the direct foaming of the green-compacts at 1310–1370 °C. The influences of the heat-treatment temperature on the relative density as well as the mechanism of the cell formation were investigated. The porosity of the obtained cellular silica and Si₃N₄/SiO₂ ceramics was within 60.0–84.0%, the cell size distribution was in the range of 10–120 μm, and the flexural strength was 9.7–16.3 MPa.     

Mechanical properties of DLC films prepared inside of micro-holes by pulse plasma CVD

Diamond-like carbon (DLC) films are metastable amorphous carbon materials with superior tribological characteristics. In order to improve wear resistance of micro-extrusion dies with numerous imperceptible holes, DLC films were deposited on the inner wall surface of model dies with holes of 2 and 0.9 mm in diameter, and 20 mm in depth by using pulse plasma CVD method. This paper will discuss how argon gas, deposition pressure and time affect the characteristics of films deposited on the inner wall surface of dies. This micro-coating method can be applied widely for inner wall surface treatment of components with thin holes.     

Oxidation resistance of SiC nanowires reinforced SiC coating prepared by a CVD process on SiC‐coated C/C composites

Oxidation protective SiC nanowires‐reinforced SiC (SiCNWs‐SiC) coating was prepared on pack cementation (PC) SiC‐coated carbon/carbon (C/C) composites by a simple chemical vapor deposition (CVD) process. This double‐layer SiCNWs‐SiC/PC SiC‐coating system on C/C composites not only has the advantages of SiC buffer layer but also has the toughening effects of SiCNWs. The microstructure and phase composition of the nanowires and the coatings were examined by SEM, TEM, and XRD. The single‐crystalline β‐SiC nanowires with twins and stacking faults were deposited uniformly and oriented randomly with diameter of 50‐200 nm and length ranging from several to tens micrometers. The dense SiCNWs‐SiC coating with some closed pores was obtained by SiC nanocrystals stacked tightly with each other on the surface of SiCNWs. After introducing SiCNWs in the coating system, the oxidation resistance is effectively improved. The oxidation test results showed that the weight loss of the SiCNWs‐SiC/PC SiC‐coated samples was 4.91% and 1.61% after oxidation at 1073 K for 8 hours and at 1473 K for 276 hours, respectively. No matter oxidation at which temperature, the SiCNWs‐SiC/PC SiC‐coating system has better anti‐oxidation property than the single‐layer PC SiC coating or the double‐layer CVD SiC/PC SiC coating without SiCNWs.     

Complex geometry macroporous SiC ceramics obtained by 3D-printing,polymer impregnation and pyrolysis (PIP) and chemical vapor deposition (CVD)

We present here an original route for the manufacturing of SiC ceramics based on 3D printing, polymer impregnation and pyrolysis and chemical vapor deposition (CVD). The green porous elastomer structures were first prepared by fused deposition modeling (FDM) 3D-printing with a composite polyvinyl alcohol/elastomer wire and soaking in water, then impregnated with an allylhydridopolycarbosilane preceramic polymer. After crosslinking and pyrolysis, the polymer-derived ceramics were reinforced by CVD of SiC using CH₃SiCl₃/H₂ as precursor. The multiscale structure of the SiC porous specimens was examined by X-ray tomography and scanning electron microscopy analyses. Their oxidation resistance was also studied. The pure and dense CVD-SiC coating considerably improves the oxidation resistance.     

Dense gypsum ceramics prepared by room-temperature cold sintering with greatly improved mechanical properties

Dense gypsum (CaSO₄·2H₂O) ceramics were successfully fabricated by a simple room-temperature cold sintering process with 5 wt% water. The relative density of gypsum ceramics increased from 89.6% to 96.8% with increasing the applied uniaxial pressure from 100 to 400 MPa during cold sintering. The relative density changed slightly for higher pressure, and microcracks were observed as well as abnormal grain growth. Both the compressive and flexural strengths reached the peaks at 98.5 MPa and 26.5 MPa for the uniaxial pressure of 400 MPa, which were improved by 2.6 and 2.0 times, respectively comparing with the bulk gypsum prepared by traditional method from α-plaster. Furthermore, the dry-pressed gypsum compacts were very fragile, and had relative densities 5–12 % lower than the cold-sintered ceramics, indicating that the slight solubility of gypsum in water (0.2 g/100 g) played a critical role in the densification, microstructural evolution and greatly improved mechanical properties of cold-sintered gypsum ceramics.