Dry wear behaviors of wear resistant composite coatings produced by laser cladding

Using different proportional mixtures of Ni-coated MoS2, TiC and pure Ni powders, new typical wear resistant and selflubricant coatings were formed on low carbon steel by laser cladding process. The microstructures and phase composition of the composite coatings were studied by SEM and XRD. The typical microstructure of the composite coating is composed of multisulfide phases including binary element sulfide and ternary element sulfide, γ-Ni, TiC and Mo2C. Wear tests were carried out using an FALEX-6 type pin-on-disc machine. The friction coefficient and mass loss of three kinds of MoS2/TiC/Ni laser clad coatings are lower than those of quenched 45 steel, and the worn surfaces of the laser cladding coatings are very smooth. Because of high hardness combined with low friction, the laser cladding composite coating with a mixture of 70% Ni-coated MoS2, 20%TiC and 10% pure Ni powder presents better wear behaviors than the composite coating with other powder blends. The composition analysis of the worn surface of GCr15 bearing steel shows that the transferred film from the laser cladding coating to the opposite surface of GCr15 bearing steel contains an amount of sulfide, which can change the micro-friction mechanism and lead to a reduced friction coefficient.     

Wear performance of Ni/ZrO<Subscript>2</Subscript> infiltrated composite layer

The Ni/ZrO2 was used as raw materials to fabricate the surface infiltrated composite layer with 1-4 mm thickness on cast steel substrate through vacuum infiltrated casting technology. The microstructure indicated that the infiltrated composite layer included surface composite layer and transition layer. Wear property was investigated under room temperature and 450 ℃. The results indicated that the abrasion volume of substrate was 8 times that of the infiltrated composite layer at room temperature. The friction coefficient of infiltrated composite layer decreased with the increasing load. The wear resistance of infiltrated composite layer with different ZrO2 contents had been improved obviously under high temperature. The friction coefficient of infiltrated composite layer was decreased comparing with that at room temperature. The oxidation, abrasive and fatigue abrasion was the main wear mechanism at room temperature. Oxidation abrasion, fatigue wear and adhesive wear dominated the wearing process under elevated temperature.     

Preparation and characterization of plasma Cu surface modified stainless steel

Cu modified layer was prepared on the surface of AISI304 stainless steel by plasma surface alloying technique.The effects of processing parameters on the thickness,surface topography,microstructure and chemical composition of Cu modified layer were characterized using glow discharge optical emission spectroscopy(GDOES),scanning electron microscopy(SEM)and X-ray diffraction(XRD).The experimental results show that the surface modified layer is a duplex layer(deposited + diffused layer)with thickness of about 26 μm under the optimum process parameters.The modified layer is mainly composed of a mixture of Cu and expanded austenite phase.The ball-on-disk results show that the modified layer possesses low friction coefficients(0.25)and excellent wear resistance(wear volume 0.005×109 μm3).The Cu modified layer is very effective in killing the bacteria S.aureus.Meanwhile,no viable S.aureus is found after 3 h(100% killed)by contact with the Cu alloyed surface.     

纳米晶工业纯铁及其Ni镀层的性能

为了探究基体材料纳米化对镀层性能的影响,采用直流电沉积方法在纳米晶工业纯铁和粗晶工业纯铁上制备了不同厚度的Ni镀层.利用扫描电子显微镜与X射线衍射仪观察并分析了镀层的组织形貌和结构.采用电化学测试和静态浸泡方法对基体和镀层进行了耐腐蚀性能研究.结果表明,纳米晶工业纯铁的基体及其Ni镀层的耐腐蚀性能略优于相同厚度下粗晶工业纯铁的基体及其Ni镀层,但随着镀层厚度的增加,这种差异逐渐减小.同时随着镀层厚度的增加,镀层表面越来越平整致密.     

球磨参数及Ni比例对Mg2Ni合金储氢性能影响研究

采用中频感应炉熔炼出铸态Mg2 Ni合金,将Mg2Ni合金与一定量的Ni粉进行混合球磨处理.系统研究在不同Ni粉添加量及球磨时间等条件下所得合金样品的结构及储氢性能.研究表明,随着Ni含量的增大及球磨时间的延长,合金的非晶纳米晶结构逐渐增多;合金的最大放电容量及循环稳定性得到明显提升;合金的表面催化活性及合金体相内的H传输能力都有了显著提高.Ni粉的作用主要在于可促进合金非晶化,同时对合金的放氢过程起到了催化的作用.     

分形维数与30Ni2B钢的韧性

分别用二次电子线扫描和数字图象法测定了冲击试样断口的分形维数，研究了３０Ｎｉ２Ｂ钢断口的分形维数和冲击韧性的关系．结果表明，试样的冲击韧性与分形线数Ｄｓｅ和ＤＨ成正相关，即冲击韧性防分形维数的增大而增加．     

时效对18Cr2Ni4WA钢性能的影响

通过对不同时效时间的处理 ,得到 18Cr2Ni4WA钢的冲击韧性值、硬度及晶粒度 ,并研究了它们之间的关系。     

分光光度计法测定服装辅件中Ni2+的含量

分析了利用测定服装辅件中Ni2+含量的化学原理及影响检测结果的因素,阐述了辅件前处理的化学方法。检测工作包括:标准曲线标定,4种样品的回收率确定,标准偏差和变异系数计算,氧化剂的加入量与二价镍含量的摩尔比应为1∶2,蔽掩剂柠檬酸适宜加入量为4～6mL。结果表明:分光光度计法测定服装辅件中二价镍含量的可靠性和实用性。     

分光光度计法测定服装辅件中Ni^2＋的含量

分析了利用测定服装辅件中Ni^2 含量的化学原理及影响检测结果的因素，阐述了辅件前处理的化学方法。检测工作包括：标准曲线标定，4种样品的回收率确定，标准偏差和变异系数计算，氧化剂的加入量与二价镍含量的摩尔比应为1：2，蔽掩剂柠檬酸适宜加入量为4～6mL。结果表明：分光光度计法测定服装辅件中二价镍含量的可靠性和实用性。     

Preparation of Ni60-Cr3C2 coating by plasma spraying, plasma re-melting and plasma spray welding on W6Mo5Cr4V2

In order to prepare heat-resistant inner layer of hot-forging die,plasma spraying,plasma re-melting and plasma spray welding were adopted.Cr₃C₂ coatings of Ni-Based were prepared respectively with 10%,20% and 30% Cr₃C₂ powder and W6Mo5Cr4V2 substrate.The coating microstructure analysis,the micro-hardness test,and the measurement of thermal parameters of coating were conducted.The experimental results show that the coating has the better thermo-physical property by using plasma spray welding method with the powder ratio of 90% Ni60 and 10% Cr₃C₂,and by this way the micro-hardness of coating can achieve 1100 HV.     

邯郸膨润土吸附含镍废水的实验研究

研究了邯郸钙基膨润土及其钠化改性土对模拟废水中Ni2 的吸附行为,探索了膨润土用量、吸附时间、pH值、初始离子浓度和温度等因素对Ni2 吸附效果的影响。结果表明,实验所用两种膨润土对Ni2 的吸附在15min时基本达到吸附平衡,吸附率随溶液pH值的增大、吸附剂用量的增加、搅拌时间的延长而增大;钠化土的吸附效果明显优于钙基土,Ni2 的去除率可达96%以上;经钠化土处理后废水中的Ni2 浓度为0.825mg/L,低于国家排放标准1mg/L。     

Cu2+和Ni2+单一和联合作用对小麦发芽和幼苗生长的影响

研究了Cu2+、Ni2+单一和联合作用对小麦(Triticum aestivum L)出芽率、根长、芽长和芽中过氧化酶(POD)活性的影响。结果表明,根长是Cu2+和Ni2+对小麦毒害的较好的监测指标,Cu2+和Ni2+对小麦根长的3d-IC50分别为3.38 mg.L-1和14.61 mg.L-1;Cu2+对小麦根长的抑制大于Ni2+,对小麦芽长抑制、出芽率的降低和芽中POD活性上升的影响小于Ni2+;Cu2+和Ni2+联合对小麦的根伸长表现拮抗,对芽伸长表现协同;1 mg.L-1Ni2+加入1~15 mg.L-1Cu2+对芽中POD活性表现出协同作用,8 mg.L-1和15 mg.L-1Ni2+加入1~15 mg.L-1Cu2+时表现出拮抗的作用。     

Theoretical calculation of the impact work in the alloying non-quenched and tempered steel

Liu et al.[1―5]1) have calculated the finishing rolling tensile strength σb, yield strength σs, elongation δ of the alloying non-quenched and tempered steel with the covalent elec-1) Liu Z L, Lin C, Guo Y C. Theoretical calculation of the finishing rolling elongation in alloying non-quenched and tempered steel. Progress in Natural Science, in presstron number nA of the strongest bond in alloying phases and the smallest electron density difference ?ρ of phase interfaces. It is calculat…     

Tribological properties of nanostructured n-Al_2O_3/Ni coatings deposited by plasma spraying

1INTRODUCTION Nanostructuredmaterialsareofprimeinterestsincetheyshouldexhibitsuperiorpropertiesin comparisonwithconventionalmaterials(i.e.mi crostructured).Thermalsprayingisregardedasoneofthepossiblemethodstodepositnanostruc turedcoatings.Researchworkshav…     

等离子喷涂NiCr/Cr_2C_3、Ni/C及其复合涂层的耐磨性能

为了加强车辆机械零件的表面防护,采用等离子喷涂工艺在304N不锈钢表面分别制备了NiCr/Cr_2C_3涂层、Ni/C涂层以及NiCr/Cr_2C_3和Ni/C复合涂层,观察了涂层组织形貌,测试了涂层硬度和耐磨性,分析了涂层的摩擦磨损机理.结果表明,3种涂层中NiCr/Cr_2C_3和Ni/C复合涂层的耐磨性能最好.金属粘结相NiCr可以起到足够的支撑作用,从而防止涂层剥离与黏着磨损的产生.Ni/C作为固体润滑剂,通过自润滑作用降低了涂层的整体摩擦系数.     

Ni2P微球的合成、表征及其电化学性能

通过简单溶剂热,以乙二醇(EG)和苯(Benzene)为溶剂,在不添加任何表面活性剂的条件下,成功制备出了Ni2P微球.结果表明,产物为纯的六方相Ni2P,形貌为由大量20nm的粒子组成的球形,微球直径介于1~3μm.通过考察反应温度、溶剂体积比及反应时间等对产物的影响,得到Ni2P微球的最佳制备条件为:反应温度160℃,溶剂比例V(EG)∶V(Benzene)=1∶1,反应时间12h.并以所制备Ni2P微球作为锂电池负极材料,研究了其电化学性能,结果表明样品的初始放电容量达1 915mAh/g.     

直流电弧法制备金属铁、镍纳米粉体

在原材料块体Fe,Ni中加入高熔点金属钨(W)、钼(Mo),采用直流电弧等离子体法在H2+Ar混合 气氛中制备Fe,Ni纳米粉体。利用X射线衍射仪(X-ray)、透射电镜(TEM)、比表面积测定仪(BET)、氧/氮测定仪 和化学分析等手段对粉体的结构、形态及粒径等方面进行了分析。结果表明,原料中加入高熔点金属W,Mo后,使 Fe,Ni金属熔球温度提高及熔球表面的氧化层被破坏,Fe,Ni纳米粉收率提高50%。高熔点金属W,Mo在粉体中 的质量分数只有0.01%左右,纳米粉纯度几乎不变。同等气氛、压强及功率条件下,加入高熔点金属W 和Mo后所 制备的粉体的平均粒度略有增大,加入W 的收率高于加入Mo的收率。     

Research on Surface Modification of 96 Al2O3 by Ni Ion Implantation

A matrix of 96 Al2O3 ceramics was implanted with Ni ion of different dosages and energies using a MEVVA implanter. Then metallic structures of copper were made on the implanted ceramics, by using selective electroless copper plating. In addition, the characteristics and microstructure of the implanted layer were studied by using the SEM, RBS and XPS. The results show that： 1） the implanted Ni exits as Ni^2, Ni^2＋, and Ni^3＋ in the surface of Al2O3 and metal Ni particles precipitate on ceramics during implantation; 2） the concentration of Ni submits to the Gauss distribution along the direction of implantation on the surface of Al2O3 and high Ni concentration on the surface can be obtained if the Ni is implanted with low energy and a high dosage and 3） Ni ion implantation can activate the surface of Al2O3 and induce electroless copper plating on the ceramics.     

XPS study of the corrosion resisting composite alloying layer obtained by double glow plasma with the brush plating Ni interlayer

The Ni-Cr-Mo-Cu multi-element surface alloying with the electric brush plating Ni interlayer on the low carbon steel substrate has been investigated. By the electrochemical method in 3.5% (mass fraction) NaC1 solution, the corrosion resistance of the composite alloying layer and single alloying layer is determined. The experimental results show that the corrosion resistance of the composite alloying layer is obviously better than that of the single alloying layer. The structure and composition of passive films formed on the two kinds of alloyed layers after electrochemical tests in 3.5% NaC1 solution have been studied using X-ray photoelectron spectroscopy (XPS). It is concluded that the double glow plasma surface alloying of low carbon steel with the electric brush plating Ni interlayer is an appropriate technique to enhance the corrosion resistance compared with the single double glow surface alloying.