煤炭固体废弃物在金属材料热加工领域的应用

综述了煤炭固体废弃物的特点及应用现状,着重介绍了粉煤灰及煤矸石等煤炭固体废弃物在金属材料热加工领域的应用,包括制备复合材料、铸造涂料、复合陶瓷涂层及渗硼保护层等,全面阐述了其制备工艺及性能特点,并指出了煤炭固体废弃物在金属材料热加工领域具有广阔的应用前景。但由于各地粉煤灰、煤矸石的化学成分差异较大,如何依据化学成分差别将其有针对性地应用在金属材料的不同加工技术中,如何进行配方设计及工艺调整等是一项值得深入探讨的问题。     

Influence of HVOF coating on the HCF of 300M low alloy steel

The ultimate methods for solving the contamination of Cr6+ is to replace the Cr electroplating with other techniques, thermal spray provides one of the best choices among those alternative techniques. The influence of coatings upon the fatigue performance of substrate, however,should be labeled as an important factor at some high level applications. The effects of both coatings manufactured by HVOF and Cr electroplating respectively on the fatigue performance of substrate are investigated in this article. These results show that the fatigue limit strength at P= 50 ,of thermal spray coating is 750 MPa in comparing with fatigue limit 726 MPa for substrate, and the fatigue life increase 25,- 150, when comparing with fatigue life of substrate at different stress levels. The fatigue life increases in the stress scope of 750-850 MPa even the area of thermal spray coating is subtracted. Cr eleetroplating coating reduces the fatigue life by 70,- 95, and the fatigue limit is only 600 MPa. Fracture analysis reveals that the main fracture is initiated at the subsurface, which is 0.2-0.5 mm away from substrate surface. The analysis also observes that the crack in the Cr electroplating propagates through the interface and finally into the substrate which hastens the formation of crack origin and the extension of crack in the substrate, however, the crack in the thermal spray coating deflects at the interface, spreads along the interface, as a result,the crack forming in the coatings has no negative influence on the main crack initiator and crack extension in the substrate.     

贾燕1,赵永涛2,张红松2

为确定ZrO2/莫来石热障涂层的单层最佳厚度,采用有限元技术研究单层厚度对ZrO2/莫来石热障涂层热冲击应力的影响。结果表明,莫来石层厚度为0.25mm时,涂层表面及ZrO2/莫来石界面处具有最大热应力,而其它莫来石层厚度时涂层内部热应力则受莫来石层厚度影响不明显。当ZrO2层厚度为0.3mm时,ZrO2/莫来石涂层中的热应力在整个横向距离范围内保持稳定,而其它情况下涂层中的热应力则与ZrO2层厚度成正比。涂层表面处的径向热应力大于ZrO2/莫来石界面处的对应值。     

离子镀TiCN和TiN工具涂层的微结构与切削性能

采用电弧离子镀技术在硬质合金铣刀和钻头上镀覆了TiCN和TiN涂层,研究并比较了两种涂层的微结构与力学性能,以及涂层铣刀的高速切削性能和涂层钻头的切削性能。结果表明,TiCN和TiN涂层同为单相的Na-Cl型结构,并都呈现(111)择优取向的柱状晶,TiCN涂层的硬度为34.6GPa,远高于TiN涂层25.1GPa的硬度。在高速铣削条件下,TiCN涂层铣刀的后刀面磨损速率仅为TiN涂层铣刀的约三分之一。TiCN涂层钻头在钻孔数为TiN涂层钻头两倍时的磨损量仍低于TiN涂层钻头。TiCN涂层的高硬度及在较高切削线速度下的减摩作用是这种涂层刀具寿命提高的重要原因。     

光学镀膜近红外膜厚监控的信号压噪

在光学真空镀膜膜厚监控过程中,近红外波段信号弱、外界干扰大、信噪比低,难于检测监控。运用相干检测、锁相放大原理,在光学真空镀膜机可见光波段监控系统的基础上,自行研制锁相放大器和改装近红外探头,成功地实现了近红外信号的压噪、放大、滤波和检测监控。     

Multilayered YSZ–Ag–Mo/TiN adaptive tribological nanocomposite coatings

Adaptive nanocomposite coatings provide low friction in broad ranges of environmental conditions through the formation of lubricious surfaces resulting from interactions with the ambient atmosphere. Designing adaptive coatings to withstand wear through repeated thermal cycles is particularly difficult since most demonstrate irreversible changes in surface composition and morphology. This permanent change in the condition of the surface limits the utility of adaptive coatings in applications where thermal cycling is expected. Moreover, some lubrication mechanisms occur over the entire coating surface in addition to the area experiencing wear, which results in a significant waste of lubricant. In an effort to increase the wear lifetime and move toward thermal cycling capabilities of solid adaptive lubricants, a multilayer coating architecture incorporating two layers of adaptive YSZ–Ag–Mo nanocomposite lubricant separated by a TiN diffusion barrier was produced. The multilayer coating lasted over five times longer than a monolithic adaptive coating of identical composition and total thickness for dry sliding tests at 500 °C in air. Analysis of the structure and composition of the films after heating suggests directed, lateral diffusion of lubricant beneath the diffusion barrier toward the wear scar as a mechanism for the increased wear life of the multilayer coating.     

Tribological Properties of Phosphor Bronze and Nanocrystalline Nickel Coatings Under PAO + MoDTC and Ionic Liquid Lubricated Condition

The friction and wear properties of phosphor bronze and nanocrystalline nickel coatings were evaluated using a reciprocating ball-on-plates UMT-2MT sliding tester lubricated with ionic liquid and poly-alpha-olefin containing molybdenum dialkyl dithiocarbamate, respectively. The morphologies of the worn surfaces for the phosphor bronze and nanocrystalline nickel coatings were observed using a scanning electron microscope. The chemical states of several typical elements on the worn surfaces were examined by means of X-ray photoelectron spectroscopy. Results show that the phosphor bronze and nanocrystalline nickel coatings exhibited quite different tribological behaviors under different lubricants. Phosphor bronze plate shows higher friction coefficient (0.14) and wear rate (3.2 × 10⁻⁵ mm³/Nm) than nanocrystalline nickel coatings (average friction coefficient is 0.097, wear rate is 1.75 × 10⁻⁶ mm³/Nm) under poly-alpha-olefin containing molybdenum dialkyl dithiocarbamate lubricated conditions. The excellent tribological performance of nanocrystalline nickel coatings under above lubricant can be attributed to the formation of MoS₂ and MoO₃ on the sliding surface. a quite a number of C, O and F products on worn surface of phosphor bronze than NC nickel coatings can improve anti-wear properties while using ionic liquid as lubricant.     

微弧等离子喷涂制备空心莫来石隔热涂层研究

采用微弧等离子喷涂方法制备了空心微珠莫来石隔热涂层。研究了涂层的结合强度、隔热性能和抗热震性能。实验结果表明：拉伸断裂发生在莫来石涂层内,涂层的平均结合强度约为5.63 MPa;稳态测量涂层隔热温度,当涂层表面温度为400℃～800℃时,涂层的隔热温度变化范围为11.5℃～40℃;热震温度为400℃～800℃间隔100℃时,涂层的抗热震次数分别为165、135、117、81和34次;涂层先从试样边沿开始剥落,并呈加速剥落的趋势。涂层失效主要原因是由于热震过程中残余应力积聚造成的。     

热氧化温度对非平衡磁控溅射TiN镀层的影响

通过SEM和XRD法,研究不同热氧化温度下闭合场非平衡磁控溅射离子镀技术制备的TiN镀层形貌、相结构及性能的变化。结果表明:非平衡磁控溅射离子镀TiN镀层在700℃以下性能基本稳定,具有良好的热氧化性能,尽管600℃时生成少量TiO2相,但600℃之前断口形貌及组织结构保持稳定;700℃时镀层的单位质量氧化增重率迅速增加,氧化曲线出现拐点,镀层失效。     

W-ThO_2电极材料的研究进展

介绍了W -ThO2 阴极材料的应用与性能特点 ,讨论了影响W -ThO2 阴极材料使用性能的因素和ThO2的作用机理 ,总结了W -ThO2 阴极材料研究中存在的主要问题。介绍了几种新近发展起来的新型W -ThO2 阴极材料 ,并提出了现阶段W -ThO2 阴极材料研究的发展方向。