(Ni-P)-SiC-PTFE化学复合镀层摩擦性能研究

通过磨损试验及表面显微观察 ,测试并分析了 (Ni P) SiC PTFE化学复合镀层的耐磨性、自润滑性等摩擦性能。实验结果表明 :(Ni P) SiC PTFE复合镀层的耐磨性、自润滑性高于化学镀 (Ni P)镀层。该复合镀层可用于高性能塑料模具的表面处理     

(SiC)p表面修饰及吸波性能研究

目的提高(SiC)P的吸波性能。方法采用低成本、环保型的化学镀镍方法对(SiC)P表面进行修饰,设计了氧化、亲水、敏化、活化系列增强前处理工艺,确定了(SiC)P表面修饰的最佳工艺流程。用SEM、EDS、XRD等分别表征了修饰前后(SiC)P形貌、成分、物相的改变,采用波导法测定了修饰后碳化硅复合粉体的介电性能,并以其为吸波剂在铝板上制备了吸波材料。结果修饰后,获得了镀层连续、无光滑(SiC)P裸露的较高质量的碳化硅复合粉体(简写为(Ni/SiC)P)。(Ni/SiC)P较原粉(SiC)P,其形貌、组成、结构发生了明显改变,且介电常数、介电损耗、吸波性能明显增强,其中,介电常数的实部增强约为22%,虚部增强约为20%。涂覆1层(Ni/SiC)P涂料,在17.12 GHz时,RL=−15.47 dB,大于涂敷2层原粉(SiC)P涂料的吸收效果。涂覆2层(Ni/SiC)P涂料,在16.11 GHz时,RL=−23.51 dB。结论采用低成本、环保型方法实现了(SiC)P表面高质量修饰,修饰后,复合颗粒(Ni/SiC)P的介电性能及吸波性能均明显提高。     

碳纳米管复合镀层在不同摩擦组合下的摩擦学行为

对CVD法制备的碳纳米管进行了表面改性和修饰,然后通过化学共沉积方法制备了高硬度的碳纳米管复合镀层,并研究了碳纳米管复合镀层在不同摩擦组合下的摩擦学行为.结果表明:经过改性处理后的碳纳米管表面拥有丰富的表面官能团,这使大量的碳纳米管复合于镀层中,从而导致了镍磷复合镀层的硬度显著提高,达到946 HV.摩擦实验得出,在润滑状态下以钢环为摩擦副,碳纳米管增强的镍磷复合镀层比传统耐磨材料SiC增强的镍磷复合镀层具有更低的摩擦系数和磨损率.此外,不同摩擦组合下的摩擦结果表明,SiC复合镀层相互摩擦时尽管拥有较低的磨损率,但其摩擦系数仍然较高,而碳纳米管复合镀层相互摩擦时表现出最低的摩擦系数和磨损率,其摩擦系数和磨损率分别为0.108 7和1.49×10-3 g/m.     

碳化硅微粉的接枝聚合改性

针对SiC微粉(＜10 μm)在精磨和抛光磨具制造中存在的微粉团聚现象,本课题根据胶体的分散稳定原理,采用硅烷偶联剂疏水预处理和丙烯酰胺在其表面接枝聚合改性SiC微粉(F1200,d50μm=3.0±0.5μm),制备出了有机包覆的改性SiC微粉.本文研究了影响SiC微粉表面改性的各种因素,用正交实验法优化出最佳工艺条件,并采用IR、Xray衍射和激光粒度等测试技术分析了改性前后SiC微粉表面物质的化学组成、结构特征及粒度分布.结果表明:SiC微粉经有机包覆改性后,表面性质发生了很大变化,但其物相结构没有改变,改性后的SiC微粉无结团现象,分散稳定性得到了改善.     

纳米二氧化钛表面改性及其在聚氨酯涂层中的分散性质

采用长链烷烃和微胶囊方法对纳米TiO2(锐钛型,粒径20nm) 进行表面改性,利用傅里叶红外光谱(FTIR)和热重分析(TGA)分别研究了改性纳米粉体的表面化学结构及接枝率,结果表明:改性纳米TiO2粉体表面成功接枝了高分子聚合物,接枝率分别为5%和12%.将改性纳米TiO2粉体(质量分数为1%～3%)与双组分聚氨酯涂料进行复合,制备了纳米TiO2/聚氨酯复合涂料,并利用扫描电子显微镜(SEM)对纳米复合涂层进行了微观检测,结果表明:微胶囊改性的纳米TiO2在涂层中的分散性最好.     

SiC颗粒表面Mo涂层的制备与分析

采用磁控溅射法在碳化硅(SiC)颗粒表面成功制备了金属钼(Mo)涂层,分析了Mo涂层的成分和形貌;为改善初始涂层成分和形貌,对镀Mo改性SiC复合粉体进行了不同工艺的结晶化热处理,重点研究了热处理对SiC颗粒表面Mo涂层形貌和成分的影响。结果表明,磁控溅射法能够在SiC颗粒表面沉积Mo涂层,随磁控溅射时间的延长,SiC颗粒表面Mo涂层的粗糙度增大,但磁控溅射后SiC颗粒表面Mo涂层为非晶态。热处理能够有效改善SiC颗粒表面Mo涂层的成分、形貌及结晶状态,在600~1200℃之间结晶化热处理过程中,随热处理温度升高,SiC颗粒表面Mo涂层形貌主要经历了以下4个阶段变化:Mo涂层初步致密化—Mo的结晶致密化—Mo涂层的聚集长大—Mo与SiC之间化学反应;相应的Mo原子的存在状态也经历了如下变化:非晶态Mo原子—晶态Mo原子—Mo_2C和MoSi_2。其中800~900℃之间为最佳热处理温度,此时Mo涂层致密均匀包覆完整。SiC表面连续均匀致密的Mo涂层,有利于改善SiC颗粒增强金属基复合材料中基体与增强体之间的界面结合并控制不利界面反应,有利于复合材料综合性能的提高,必将扩大SiC颗粒作为增强体的应用范围。     

改性SiC陶瓷浆料分散流动性的研究

本项目采用疏水预处理和接枝聚合的方法对SiC微粉进行表面改性,通过研究SiC微粉颗粒表面的zeta电位,pH值对浆料的分散性和流动性的影响,制备出了固相体积分数为50%,黏度低于0.42mPa.s,在水基体系中分散流动性能较好的SiC悬浮浆料。测试结果表明:改性SiC微粉在酸性(pH=2～4)或碱性(pH=8～12)条件下,均可获得较大的zeta电位,其分散稳定性均得到了较大的改善,可以有效的改善水浇注陶瓷磨具的成型性能。     

表面强化及改质技术

真空离子镀Al-SFY涂层的高温性能研究;Ni离子注入纯锕的表面改性;CrNiMo不锈钢激光熔覆NiCrSiB涂层空蚀行为;YG8电极在氲气和硅油中对Ti17的电火花表面改性研究;化学气相沉积法制备SiC／SiO2梯度复合涂层的热力学分析     

表面强化及改质技术

真空离子镀Al-SFY涂层的高温性能研究;Ni离子注入纯锕的表面改性;CrNiMo不锈钢激光熔覆NiCrSiB涂层空蚀行为;YG8电极在氲气和硅油中对Ti17的电火花表面改性研究;化学气相沉积法制备SiC／SiO2梯度复合涂层的热力学分析     

WC/W_2C_P表面改性对WC/W_2C_P-NiCrBSi/耐热钢复合材料磨损性能的影响

以铸造碳化钨(WC/W2C P)为增强颗粒,利用真空熔烧工艺制备了一种结构增韧的金属基复合材料。利用SEM,EDS,显微硬度测试和图像分析等手段研究了WC/W2C P表面改性前、后复合材料中颗粒增强区域(WC/W2C P-Ni Cr BSi)的微观组织结构和性能;利用环-盘式磨损试验机研究了WC/W2C P表面改性对复合材料在室温和600℃时的磨料磨损性能的影响。结果表明,经表面改性后WC/W2C P在Ni Cr BSi基体中的分解得到了有效抑制,颗粒内部WC/W2C共晶组织的含量与未改性的颗粒相比提高了1.6倍。以表面改性的WC/W2C P为增强颗粒能显著降低复合材料在室温和高温时的磨损率。在600℃时磨损表面形成了层状结构的保护膜,致使复合材料的磨损率低于室温时的磨损率。     

Ni-SiC复合镀层组织和性能的研究

在A3钢板上制备了含有微米和纳米 SiC 的两种镍基复合镀层, 利用扫描电镜观察镀层表面显微组织, 利用X射线能谱分析SiC的分布情况, 通过纳米显微力学探针测量镀层微区硬度. 结果表明 : SiC 颗粒在镀层中分布均匀; SiC 颗粒附近复合镀层的硬度是纯镍镀层的 3 倍, 微米 SiC 复合镀层的弹性模量比纯镍镀层提高了近 5 倍, 而纳米 SiC 复合镀层则提高了 15 倍以上, 但随着远离 SiC 镀层硬度和弹性模量都有明显下降; SiC 颗粒的加入能够有效阻止镀层表面发生变形, 纳米 SiC 的作用更明显.     

Ni-SiC复合电铸层内应力实验研究

提出通过掺杂SiC颗粒来减小Ni微电铸层内应力的新方法,基于UV-LIGA工艺制作了纯镍电铸层和Ni-SiC复合电铸层,采用X射线衍射法测量微电铸层的内应力,分析SiC颗粒对微电铸层内应力的影响效果。利用L_9(3~4)正交试验考查了铸液中SiC浓度、电流密度、搅拌转速及电铸温度等工艺参数对复合电铸层内应力的影响。结果表明:掺杂SiC颗粒能有效减小微电铸层内应力,电流密度和铸液中SiC浓度对内应力的影响大于搅拌转速和电铸温度。复合电铸层内应力实验的最优工艺参数为:SiC浓度20 g/L,电流密度1 A/dm~2,磁力搅拌转速600 r/min,电铸温度50℃。     

INTERFACIAL STRUCTURE AND PHASE REACTION IN SiC/NiCr ALLOY JOINT

1.~onSiCamongStbasecerdricsPOssessessuperiormechanicalpropertiesathightemperatures.InordertoexpandtheengineeringaPPlicationsoftheceramics,thebondingofSiCtometalisreqUiredbecausethemetalscompensatetheworseworkabilityandbrittlenessoftheSiC.TheknowledgeofinterfacestructuresandreactionphasesattheinterfacebetweenSiCandmetalisnecessarytOobtainthehighreliableSiC/metaljoint.SeveralstudiesconcerningbondingmechanismsbetweenSiCandmetalsofTi,Cr,NbandTa[l--53.AlthoughheatjresistantNiandNi--Crallo…     

SiC纳米线对Ni-Cr-P钎料及Ni-Cr-P/Q235焊点组织与性能影响

采用具有优良高温强度、高热导率、高耐磨性能和耐腐蚀性能的SiC纳米线为Ni-Cr-P钎料的添加物,研究了钎料/焊点的组织与性能。结果表明,钎料的组织由Ni(Cr)固溶体、Ni₃P固溶体以及Ni(Cr)和Ni₃P共晶组织组成,微量的SiC纳米线可以显著细化基体组织,使焊点抗剪切强度提高29.6%。SiC纳米线的添加使钎料的熔化温度提高约4℃,显著促进钎料在Q235基板表面的润湿性,增幅达到12.5%。然而,过量添加SiC纳米线会显著粗化基体组织,降低钎料的润湿性和焊点的抗剪切强度。在不同SiC含量的Ni-Cr-P钎料中,Ni-Cr-P-0.1SiC钎料/焊点具有明显的优越性。     

Room and high temperature wear behaviour of Ni matrix micro- and nano-SiC composite electrodeposits

In the frame of the research domain of the production of metal matrix composite deposits the aim of this work is the production of Ni matrix composite coatings containing either micro- or nano-SiC particles and their characterization. The electrodeposition has been carried out under DC conditions using a nickel sulfammate plating bath into which the particles were suspended. The composite coatings were tested and compared to pure nickel deposits regarding the microstructure, microhardness and wear resistance under high load at both room temperature and 300 °C. The codeposition of the SiC particles changed the microstructure of the nickel matrix and the preferential orientation of the Ni grains leading to a noticeable improvement on both microhardness and wear resistance. The pure nickel deposit presents a pseudocolumnar structure and a preferential [100] orientation. The codeposition of the μSiC particles slightly modified the dimensions and the orientation of the pseudocolumns and led to a [110] preferential orientation of the Ni grains. The microstructural modifications and the presence of the SiC particles in the metal matrix lead to a 51% increase of the microhardness, a 63% decrease of the wear coefficient at 300 °C while it did not offer any improvement at the wear resistance at room temperature. The codeposition of nSiC particles leads to a noticeable grain refinement and the loss of a preferential orientation. The microstructural modifications in this case lead to a 67% increase of the microhardness, a 70% decrease of the wear coefficient at room temperature and an 88% decrease of the wear coefficient at 300 °C in comparison to the pure nickel deposits. The improved wear resistance of the Ni/nSiC deposits is attributed to their compact microstructure and to the absence of a preferential orientation which was maintained also after wearing, contrary to the other two types of deposits.     

Improving corrosion resistance of aluminium metal matrix composites using cerium sealed electroless Ni–P coatings

Abstract

A conversion coating treatment using cerium salts was developed for the surface sealing of electroless nickel–phosphorus (Ni–P) coatings on carbon fibre reinforced aluminium (Cf/Al) composites. The corrosion resistances of uncoated and coated materials (i.e. the Ni–P coating, the Ce conversion coating and Ce sealed Ni–P coatings) were evaluated in 3·5 wt-%NaCl solution using potentiodynamic polarisation and electrochemical impedance spectroscopy. Ce sealed Ni–P coating showed the highest corrosion resistance and clearly improved the overall corrosion resistance of Cf/Al composites. Thus, the Ce sealed Ni–P coating had no obvious microcracks that were generally evident in the more conventional Ce conversion coatings. This is presumed to occur because the electroless nickel surface is relatively homogeneous, compared with the Cf/Al composite surface on which different local coating thicknesses would encourage increased microcrack formation. X-ray photoelectron spectroscopy analysis showed that the Ce conversion coating mainly contained both Ce³⁺ and Ce⁴⁺ species; however, Ce⁴⁺ species were the dominant oxidation state on Ce sealed Ni–P coatings.     

镍元素对反应烧结碳化硅导电性的影响

研究了镍对反应烧结碳化硅导电性的影响,结果表明,随含镍量的增加,反应烧结碳化硅的电阻率降低,随测试温度提高,含镍的碳化硅虽呈现负的温度系数,但幅度减小,９００℃保温,随时间延长,电阻率几乎不变,这说明镍可改善反应烧结碳化硅的导电特性,同时还分析了镍的存在方式及其相结构。     

Effect of α-Al2O3 coatings on the interface of Ni/SiC composites prepared by electrodeposition

This paper describes an investigation on the effect of α-Al₂O₃ coating on the interface between nickel and SiC particle. Uniform, dense and well-adhered α-Al₂O₃ coatings were obtained on the surface of SiC particles by sol–gel technology. The nickel-based composites reinforced with α-Al₂O₃-coated SiC particles (CS_p) or uncoated SiC particles (UCS_p) prepared by composite electrodeposition were heated at 600 °C to study the reactivity and the resulting interfaces. The results showed that the Ni/CS_p composites presented excellent thermal stability without interfacial reaction, while nickel silicide formed in the Ni/UCS_p composites. It indicated that high-temperature interfacial reaction between SiC particles and nickel matrix was efficiently inhibited by the α-Al₂O₃ coatings. Moreover, great differences of the local mechanical properties of interfaces were observed by the nanoindentation characterization.     

SiCP颗粒增强Al基复合材料的瞬间液相连接

采用Ni箔和Cu/Ni/Cu多层箔作中间层在923K进行了SiC颗粒增强铝基复合材料的瞬间液相连接。研究表明,无压连接时,接头强度随保温时间延长有所增高,但界面处会存在纯金属（无增强颗粒）区域和氧化物夹杂,是导致接头强度不高的主要原因。加压TLP连接则能有效改善界面组织和接头性能。采用Cu/Ni/Cu多层箔作中间层加压连接时接头强度可达189．6MPa,约为母材强度的85％。本文对压力的作用和复合材料TLP连接界面特性进行了讨论。