Effects of slurry pack cementation temperature on microstructure and wear resistance of Ti-Al co-deposited coating on copper plated nickel layer

In order to improve the wear resistance properties of copper substrate, a layer of electroplated nickel was firstly deposited on copper substrate, subsequently these electroplated specimens were treated by slurry pack cementation process with a slurry pack cementation mixture composed of TiO2 as titanizing source, pure Al powder as aluminzing source and also a reducer for titanizing, an activator of NH4Cl and albumen （egg white） as cohesive agent. The Ti-Al coating was fabricated on the surface of electro-deposited nickel layer on copper matrix followed by the slurry pack cementation process. The effects of slurry pack cementation temperature on the microstructures and wear resistance of Ti-Al coating were studied. The results show that the microstructure of the coating changed from NiAl＋Ni3（Ti,Al） to NiAl ＋Ni3（Ti,Al）＋Ni4Ti3 to Ni4Ti3＋NiAl, and to NiAl＋Ni3（Ti,Al）＋NiTi with slurry pack cementation temperature ranging from 800 ℃ to 950 ℃ in 12 h. The friction coefficient of Ti-Al coating decreased and the hardness increased with increasing the slurry pack cementation temperature. The minimum friction coefficient was 1/3 and the minimum hardness was 5 times larger than that of pure copper.

Preparation and Microstructure of a Si-Mo Fused Slurry Coating on Carbon/Carbon Composites for Oxidation Protection

A coating of composition Si-40Mo (wt pct) was prepared by fused slurry coating method on the two-dimensional carbon/carbon (2D-C/C) composite to improve oxidation resistance. In the procedure of the fabrication, pure St slurry inner layer in the pre-coating was necessary to apply because of infiltration of liquid Si into the substrate during the sintering. The coating consists of Si continuous phase and MoSi2 particles. In addition, the infiltration of Si into the substrate and the SiC reaction layer between the coating and the C/C composite were observed. Oxidation behavior of coated and uncoated C/C composites was studied in cyclic mode. The oxidation resistance and the thermal shock resistance of the Si-Mo fused slurry coating were quite excellent at 1370℃.

Effect of pattern coating thickness on characteristics of lost foam Al-Si-Cu alloy casting

An experimental study on lost foam casting of an Al-Si-Cu alloy was conducted. The main objective was to study the effect of pattern coating thickness on casting imperfection and porosity percentage as well as eutectic silicon spacing of the alloy. The results showed that increasing slurry viscosity and flask dipping time influenced the casting integrity and microstructural characteristics. It was found that thinner pattern coating produced improved mould filling, refined microstructure and higher quality castings containing less porosity.

Ablation resistance and mechanism of SiC/ZrC-ZrB2 double layer coating for C/C composites under plasma flame

To improve the ablation resistance of carbon/carbon(C/C)composites,a SiC/ZrC-ZrB2 double layer coating was fabricated by pack cementation and slurry-sintering method.The ablation resistance of the SiC/ZrC-ZrB2 coating was tested under plasma flame above 2300°C.The results indicate that the SiC/ZrC-ZrB2 double layer coating exhibits superior ablation resistance than the ZrC-ZrB2 single layer coating.After being ablated under the plasma flame for 20 s,the mass and linear ablation rates of the ZrC-ZrB2 coating are 0.89 mg/s and 15.3μm/s,while those for SiC/ZrC-ZrB2 coating are 0.09 mg/s and 24.15μm/s,respectively.During ablation,the SiC inner layer can generate SiO2 glass and result in the formation of ZrO2-SiO2 molten film.Compared with the ZrO2 molten film formed on the ZrC-ZrB2 coating surface,the ZrO2-SiO2 molten film with lower oxygen diffusion rate and viscosity enables the SiC/ZrC-ZrB2 coating to have better self-healing ability.Therefore,the enhanced ablation resistance of the SiC/ZrC-ZrB2 coating can be attributed to the formation of dense ZrO2-SiO2 molten film under the plasma flame.

Microstructure and isothermal oxidation of 3Al_2O_3·2SiO_2/SiC coating on high and low density carbon-carbon composites

Carbon-carbon composite （C/C） materials are prone to severe oxidation and volatilization problems. To address these issues, mullite （3Al2O3.2SiO2）/silicon carbide （SIC） coatings were deposited on C/C composite substrates characterized into high and low densities. The coatings were applied by a two-step approach： pack cementation and silica sol based slurry coating processes. The relationship between the microstructure of 3Al2O3·2SiO2/SiC coatings and C/C substrates during isothermal oxidation cycle at 1 500 ℃ was investigated using X-ray diffractometer （XRD） and scanning electron microscope （SEM） mounted with energy dispersive spectrometer （EDS）. The results indicate that the density of the substrates has a marked effect on the coatings. Dense, thick and well-bonded coatings are obtained in the high density substrate. After 106 h of isothermal oxidation, the high density substrate with 3Al2O3-2SiO2/SiC coating offers effective protection as compared to low density substrate suffering recession.

Rheological Behaviour, Synthesis and Performance of Smart Thermal Barrier Coating Systems Based on Hollow Alumina

The stability of three water-based slurries containing different loads of Al microparticles was measured by laser scattering. The slurries displayed a Newtonian behaviour and the evolution of viscosity over nine days was found to be constant. Ground surfaces of nickel were also wetted similarly irrespective of the Al content in the slurries (30, 40 or 50 wt%) thereby demonstrating that the 1/10 PVA/H2O water based slurries are adequate for spraying. After deposition and annealing of the as-sprayed coatings, a thermal barrier coating system was formed with a top coat of hollow alumina spheres, an intermediate thermally grown oxide and a bottom aluminized bond coat. The coating system is shown to display very low thermal conductivity and remarkable oxidation resistance at high temperatures.

Oxidation behavior of oxidation protective coatings for C/C-SiC composites at 1500 ℃

Porous carbon/carbon preforms were infiltrated with melted silicon to form C/C-SiC composites. Three-layer Si-Mo coating prepared by slurry painting and SiC/Si-Mo multilayer coating prepared by chemical vapor deposition(CVD) alternated with slurry painting were applied on C/C-SiC composites, respectively. The oxidation of three samples at 1 500 ℃ was compared. The results show that the C/C-SiC substrate is distorted quickly. Three-layer Si-Mo coating is out of service soon due to the formation of many bubbles on surface. The mass loss of coated sample is 0.76% after 1 h oxidation. The sample with SiC/Si-Mo multilayer coating gains mass even after 105 h oxidation. SiC/Si-Mo multilayer coating can provide longtime protection for C/C-SiC composites and has excellent thermal shock resistance. This is attributed to the combination of dense SiC layer and porous Si-Mo layer. Dense SiC layer plays the dual role of physical and chemical barrier, and resists the oxidation of porous Si-Mo layer. Porous Si-Mo layer improves the thermal shock resistance of the coating.

Efect of Micro Abrasive Slurry Jet Polishing on Properties of Coated Cemented Carbide Tools

Owing to the popularization of coating technology, physical Vapor Deposition (PVD) coated tools have become indispensable in the cutting process. Additionally, the post-treatment of coated tools applied to industrial production can efectively enhance the surface quality of coating. To improve the processing performance of coated tools, micro abrasive slurry jet (MASJ) polishing technology is frst applied to the post-treatment of coated tools. Subsequently, the efects of process parameters on the surface quality and cutting thickness of coating are investigated via single-factor experiments. In the experiment, the best surface roughness is obtained by setting the working pressure to 0.4 MPa, particle size to 3 μm, incidence angle to 30°, and abrasive mass concentration to 100 g/L. Based on the results of the single-factor experiments, combination experiments are designed, and three types of coated tools with diferent surface qualities and coating thicknesses are obtained. The MASJ process for the post-treatment of coated tools is investigated based on a tool wear experiment and the efects of cutting parameters on the cutting force and workpiece surface quality of three types of cutting tools. The result indicates that MASJ machining can efectively improve the machining performance of coated tools.

Fabrication of ZrO_2/Mo-Si/Ni Functionally Graded Material by Dip-Coating

A slurry dip-coating technique was developed for fabrication of Zr02/Mo-Si/Ni functionally graded material (FGM)on the stainless steel substrate. The rheological behavior of ZrO2-Ni-ethanol slurry was characterized by viscositytest. The amount of polyvinyl butyral (PVB) additives, which served as the dispersant and binder in ZrO2-Ni-ethanolslurry, was optimized. The results showed that the characters of mixed slurries with added 9 vol. pct (relativelyto total powders) MoSi2 powders prepared by mechanical alloying changed little. The stainless steel substrate wascoated several times by dipping in the slurries, and followed by drying in air every dipping. After debinding in Arin graphite die, the coated FGM plate was finally hot pressed at 1300℃ for 1 h under the pressure of 5 MPa in Arin the same die. Microstructural observations of the sintered FGM specimens revealed that the graded layers wereformed on the stainless steel substrate, in which no cracks were observed.

Current collectors’ effects on the electrochemical performance of LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2) suspension electrodes for lithium slurry battery

Take after the advantages of lithium-ion battery (LIB) and redox flow battery (RFB), semi-solid flow battery (SSFB) is a promising electrochemical energy storage device in renewable energy utilization. The flowable slurry electrode realizes decouple of energy and power density, while it also brings about new challenge to SSFBs, electron transport between active material and the out circuit. In this consideration, three types of current collectors (CCs) are applied to study the resistance and electrochemical performances of slurry cathodes within pouch cells for the first time. It proves that the electronic resistance (Re) between slurry electrode and the CC plays a decisive role in SSFB operation, and it is so large when Al foil is adopted that the cell cannot even work. Contact angle between Ketjen black (KB) slurry without active material (AM) and the CC is a preliminarily sign for the Re, the smaller the angle, the lower the resistance, and the better electrochemical performance of the cell.

The Microstructure and Oxidation Resistance of The Microstructure and Oxidation Resistance of Slurry Method on Rene 80 Superalloy

The slurry method is one of the oldest techniques of deposition of aluminide coating on the nickel superalloy, titanium alloys and steel. It is characterized by relatively low costs of its realisation and necessary equipment. This method en-ables a simple modification of chemical composition of the coating through addition of different powders. The author showed study on the possibility of modification of the Al-Si slurry chemical composition used for aluminide coating deposition by addition of MeCrAlY powder. The slurry was deposited by immersion than the diffusion treatment at 950℃ for two hours was applied. The thickness of obtained coatings was in the range of 30 - 65 μm.

锂电负极废涂布浆料破胶减容与资源化利用

锂电负极废涂布浆料含水率高、胶态分散稳定性强,难以过滤。本文研究了废涂布浆料的胶态特性,分析了废浆料的高效破胶分离机理,并对其资源化进行了初步探索。羧甲基纤维素钠(CMC-Na)解离产生的羧基负离子(R-COO-)提供的静电斥力及苯乙烯-丁二烯橡胶(SBR)在颗粒间形成的空间位阻力是废浆料胶态稳定性的根本原因。酸度的降低能够抑制浆料中CMC-Na的解离,减少吸附于石墨颗粒表面的带电基团R-COO-,削弱静电斥力,造成颗粒团聚,并破坏SBR的架桥作用。pH=2.0时,废浆料破胶过滤效率较佳,过滤常数为0.0741m2/s,含水率降低48个百分点;X射线三维显微成像分析(X-CT)表明细微颗粒团聚破胶的同时,保留的静电斥力能够降低过滤阻力,促进滤饼孔道结构的发育,生成大孔隙半径,长喉道的渗流网络减少滤饼孔道吸附水的量;分离所得固相碳材对亚甲基蓝、铬(Cr^(6+))、COD的吸附量分别为435mg/g、0.645mg/g、87mg/g,满足《工业水处理用活性炭技术指标及试验方法》(LY/T3279—2021)优级品标准。

Fabrication of LSGM thin films on porous anode supports by slurry spin coating for IT-SOFC

La0.9Sr0.1Ga0.8Mg0.2O3-δ（LSGM） and La0.7Sr0.3Cr0.5Mn0.5O3-δ（LSCM） powders were synthesized by glycine-nitrate process, and LSGM electrolyte thin film was successfully fabricated on porous anode substrate of LSCM by slurry spin coating technology. Some technical parameters for the preparation of LSGM thin films were systematically investigated, including ink composition,sintering temperature, and spin coating times. The electrolyte films with the best compactness and somewhat rough are obtained when the operating parameters are fixed as follows: the content of ethyl cellulose as binder is 5 wt%, the content of terpineol as modifier is 5 wt%, the optimum coating cycle number is 9 times, and the best post-deposition sintering temperature is 1,400 °C for 4 h.

应用于船舶尾气NO_(x)去除的SCR催化剂涂覆工艺影响因素研究

涂覆工艺对于整体式涂覆型SCR催化剂至关重要。通过对催化剂浆料制备过程以及涂覆过程中的关键影响因素的探究,考察了分散剂、增稠剂及对应添加量、pH和固含量对浆料涂覆效果及活性测试结果的影响。通过比较不同涂覆方式、浆料搅拌时间、干燥温度及时间、成型焙烧温度及时间,对涂覆工艺进行过程优化选择。结果表明:通过最优方案制备的涂覆型催化剂在250~450℃的条件下反应活性均在85%以上,在315℃的条件下运行30 h脱硝活性仍能稳定在90%以上。系统地梳理了涂覆过程中关键参数的选择及应用,为整体式蜂窝状涂覆式催化剂的制备提供了指导。

Slurry erosion behaviors of P110 steel and chromizing coating in liquid-solid two-phase flow

A chromizing coating was formed on P110 oil casing tube steel (P110 steel) via pack cementation to improve its performance and increase the lifetime during operation. The slurry erosion behaviors of the P110 steel substrate and the chromizing coating were assessed in a liquid-solid two-phase flow condition. The results showed that the obtained coating exhibited higher surface hardness, lower mass loss, and lower slurry erosion rate than those of P110 steel. The chromizing treatment has significantly improved the surface hardness and slurry erosion resistance of P110 steel.

用于船舶尾气NO_(x)治理的蜂窝状整体式NH_(3)-SCR催化剂研究进展

随着船舶运输行业的蓬勃发展,船舶尾气带来的污染也愈发严重,氮氧化物(NO_(x))为其中主要污染物。氨气-选择性催化还原(NH_(3)-SCR)是目前最有效的脱硝方法,催化剂是技术的核心部分。整体式催化剂具有机械强度高和传热性能好等特点,是应用最广泛的商业催化剂。文章综述了用于NH_(3)-SCR的船舶整体式催化剂载体的预处理方法、挤出成型法和涂层涂覆法及其优缺点,重点总结了浆料涂覆法的涂覆式催化剂研究进展。船舶排放尾气成分复杂,二氧化硫、水蒸气、颗粒物等都会对NH_(3)-SCR催化剂产生不利影响,因此对催化剂耐中毒性能机理、催化剂的SCR活性和耐复杂污染物中毒性能进行了综合分析和总结。

铁铝土泥浆包覆与淬灭强化荔枝木炭化物的碳固存率

生物质炭作为一种富碳多孔材料,具有固碳、减污和培肥等多重功效。基于当前限氧高温热裂解制炭技术及炭改性方法,该研究以亚热带地区常见的荔枝木为原材料、选取铁铝土制成泥浆,通过泥浆包覆和淬灭实现生物质“自限氧”和“水”淬灭,探讨铁铝土泥浆在荔枝木炭化过程中的作用及其对炭质的影响机理。结果表明:铁铝土泥浆包覆和淬灭制得的荔枝木炭的碳含量和碳固存率最高,分别为83.5%和83.9%,较无包覆水淬灭炭品的碳含量和碳固存率提高了16.7和37.8个百分点。扫描电镜-能谱分析的结果表明,铁铝土泥浆包覆和淬灭生成的炭品的碳骨架结构规整且其表面有铁铝矿物负载。一方面,泥浆通过涂层包覆形成了包覆壳,以物理阻隔作用截留了碳(防止炭化物中的碳在持续燃烧中生成COX);另一方面,铁铝矿物在高温热裂解过程中与炭化物结合,形成了矿质(Fe/Al)-碳质复合体,实现了碳固存。研究可为生物质炭的制备提供新的便捷、廉价的技术思路,以生物质就地炭化和应用的碳负排放方案助力碳中和。

基于PAA黏结剂的陶瓷浆料界面研究

聚丙烯酸(PAA)黏结剂作为一种常用的表面改性剂,在锂离子电池极片涂布过程中对极片边缘陶瓷浆料的界面性能起着重要的作用。本研究旨在探究PAA黏结剂对陶瓷浆料界面性能的改善效果。通过固相共混法,使用PAA替代传统聚偏氟乙烯(PVDF)黏结剂制备了陶瓷浆料,并对浆料流变特性及接触角进行测试。结果显示,相对于传统PVDF体系陶瓷浆料,接触角降低至22.7°,且浆料黏度回弹率≤10%,显著提升了陶瓷浆料的润湿性和稳定性,这使得陶瓷浆料更易涂布于基材表面,并与正极活性物质的融合区形成均匀的涂层。这些研究结果为PAA黏结剂在锂离子电池陶瓷浆料制备和应用中的设计和优化提供了重要的理论基础。

用超声/电声谱监测锂电池正极浆料的合浆及包覆质量

在前期工作的基础上,利用超声/电声学方法对锂电池浆料合浆工艺的质量控制参数进行了探索,对不同来源和不同批次的N-甲基吡咯烷酮(NMP)体系磷酸铁锂电池(LFP)浆料进行了粒度、zeta电位及其微观电学参数的测定。结果显示,对于分散较好的合格样品,浆料的粒度、zeta电位、表面电荷密度可基本重现;而对于原料粒度检测不合格的样品,不仅浆料粒度分布呈现双峰,zeta电位有较大的波动,且表面电荷密度降低,批次间不稳定。研究表明,超声法直接测定锂电池合浆过程中的原浓浆料粒度直观有效,对于工艺质控非常重要;在合浆过程中,因导电添加剂团聚的存在,很难均匀包覆在LFP颗粒上。因此,zeta电位和双电层厚度可以成为导电剂是否分散和包覆均匀的关键质量控制参数。

Nb-Ti-Al基合金的防护涂层研究及其抗氧化性能机理分析

利用真空电子束熔炼与电弧炉技术合成了Nb-Ti-Al基合金,利用料浆熔烧技术在合金表面制备了Si-Cr-W防护涂层,并对1250℃条件下的涂层抗氧化性能进行了评估,同时采用扫描电子显微镜和能量散射光谱研究分析了氧化前后的涂层微观形态和元素分布。研究结果表明:防护涂层的主要成分包括Nb、Ti、Cr、W等金属硅化物,其在高温下抗氧化机制为通过金属硅化物的氧化分解,生成SiO2和复合金属氧化物层,从而有效阻挡氧气的渗透。在经历了100 h的氧化测试后,涂层的外部结构因氧化而呈现出疏松的状态,但内部结构仍然保持着致密的特性,验证了该涂层在高温条件下具有出色的抗氧化性能。