半导体激光熔覆高硬Ni基WC涂层

为提高球阀的使用寿命,通过激光熔覆技术,在304钢基体上制备Ni28+WC涂层,并研究WC含量和激光器功率对涂层表面性能的影响.借助金相显微镜、显微硬度计研究了不同含量WC下涂层的裂纹情况、稀释率及硬度.研究结果表明:随着WC含量升高,涂层硬度显著提高,稀释率逐渐降低,增加激光输出功率可以促进WC颗粒融化从而提高稀释率,当WC含量为30%时,涂层无裂纹,平均显微硬度达到580Hv0.1,稀释率为4.9%,涂层与基地之间实现冶金结合.WC含量高于40%时,由于未融化和析出的WC颗粒的增多,涂层开裂.     

亚音速火焰喷涂钛／生物微晶玻璃涂层结构研究

采用亚音速火焰喷涂方法及涂层处理技术,以Ti6A14V为基体,喷涂钛-生物微晶玻璃,涂层经700℃晶化处理．采用TG—DSC、X射线衍射法（XRD）测试粉体相组成,金相显微镜、扫描电子显微镜（SEM）观察涂层显微结构．结果表明：亚音速火焰喷涂制备钛／生物微晶玻璃涂层表面存在大量孔洞结构,有利于骨组织的生长,提高种植体与骨组织间的结合强度．钛-生物微晶玻璃涂层结合紧密,未见明显裂纹,Ti—BG过渡层起到了缓解涂层应力、提高涂层的结合强度的作用．     

H13模具钢等离子熔覆WC/Ni基复合涂层研究

以Ni60+35%WC合金粉末为原料,采用等离子熔覆技术,在H13模具钢基体上熔覆WC/Ni基复合涂层。借助SEM、XRD分析涂层的显微组织;利用显微硬度计测试涂层的显微硬度;通过环-块磨损实验在MM-200磨损试验机上评估涂层的耐磨性能;采用线性极化法研究涂层在3.5%NaCl溶液中的耐蚀性能。结果表明:涂层组织均匀细小,主要由γ-(Ni,Fe)树枝晶以及枝晶间的γ-(Ni,Fe)与Cr23C6、Fe3W3C形成的共晶结构组成,在涂层底部分布有WC增强相;涂层的显微硬度可达590~650HV0.3;在室温干滑动磨损条件下,涂层的耐滑动磨损性与基体相比提高了1倍以上。在3.5%NaCl溶液中,涂层的耐腐蚀性能优于H13钢基体。H13钢经等离子熔覆WC/Ni基复合涂层后耐磨性能、耐蚀性能得到提高,可用于H13钢制模具的表面磨损修复。     

激光沉积铁基涂层微观组织与耐磨性能研究

为适应恶劣工况条件,满足精密装备对高功率小体积复杂化的发展需求,提高中碳钢材料关键部件工作表面耐磨性能,国内外主要的解决办法是利用激光沉积耐磨涂层代替传统表面淬火。本文以42Cr Mo钢作为基材,高功率CO2激光作为热源,使用同轴送粉的填料方式在基材表面涂覆激光沉积层,选取激光功率P=2.5k W,扫描速度v=0.3m/min。用Fe106、Fe106+Ni/WC的铁基涂层和表面激光高频淬火对比研究,研究Ni/WC颗粒对激光沉积铁基涂层性能的影响规律。结果表明:WC增强相的加入可以使铁基涂层中的增强相增多,还能使涂层组织细化。与高频淬火相比,单一的Fe106沉积层晶粒粗大,耐磨性能未出现明显提高;添加Ni/WC的涂层中由于硬质颗粒相和晶粒细化的影响,使涂层耐磨性显著提高。提高程度是高频淬火的1.5倍、Fe106沉积层的1.7倍和基材的2.86倍。     

钛合金表面激光熔覆Cr3C2/Ni基合金复合涂层的微观组织

将质量分数为25％的Cr3C2／Ni基合金混合粉末预置在TCA合金表面，利用5kW横流CO2激光器进行激光熔覆试验，得到Ni基Cr3C2复合涂层．利用SEM和XRD对熔覆层的微观组织和相组成进行了分析，采用HXD—1000T数字式显微硬度计测量了熔覆层的硬度．结果表明，Ni＋Cr3C2复合涂层存在γ-Ni、TiC、CrTC扑M23（C，B）6和CrB等相，熔覆层硬度在600～900HV之间．     

氩弧熔覆原位自生Ti(C、N)-WC增强Ni60A复合涂层的研究

以Ni60A、TiC、TiN、WC、Co粉为原料,在Q235钢的表面用氩弧熔覆原位合成技术制备了Ti(C、N)-WC增强镍基复合材料涂层.研究了涂层的显微组织、化学成分、硬度变化和摩擦磨损特性.熔覆层组织主要由富Ni的γ(Ni,Fe)相、Ti(C、N)、WC和(Fe,Cr)xC等组成.涂层的显微硬度和耐磨性分别是基体Q235钢的6.5倍和10倍.显微硬度由表及里呈先上升后下降的阶梯状趋势,到热影响区时又明显降低.基体Q235钢的磨损机制为黏着磨损和磨料磨损,而复合涂层的的磨损形式主要是磨屑充当第三体引起的磨粒磨损.     

高Ni—Cr合金涂层防护锅炉受热面高温腐蚀的性能研究

针对电站锅炉受热面高温腐蚀的影响,采用电孤喷涂工艺,基体为锅炉受热面常用材料,喷涂国产高Ni—Cr合金涂层,对比FeCrAl涂层和T91材质,研究高温条件下的热腐蚀实验和热震实验,结合腐蚀动力学曲线与金相分析得到的孔隙率,说明国产高Ni—Cr合金在腐蚀防护上具有良好的性能,为今后电厂采用高Ni—Cr合金热喷涂涂层的防高温腐蚀应用提供借鉴．     

金属基陶瓷涂层的耐高温及抗热冲击性能

以自制无机胶粘剂、通过添加耐高温耐磨陶瓷骨料A12 O3,WC,SiC混合后涂覆于A3钢表面制得陶瓷涂层,研究了调胶比（氧化铜与磷酸盐的配比）、骨胶比（胶粘剂与陶瓷骨料的配比）不同对金属基陶瓷涂层耐高温及抗热冲击性能的影响;并分析了金属基体与陶瓷涂层间的结合机理．结果表明：调胶比为0．5g／ml此涂层能承受1300℃以上的高温．骨胶比比为0．30：1（质量比）时,制备的陶瓷涂层抗热冲击性能最佳,能承受600～700℃的16次以上的热震试验．     

等离子熔覆铁基合金＋镍包WC复合涂层热力学分析

基于X射线衍射分析和Thermo-calc软件热力学平衡相计算,研究了在Q235钢基体上等离子熔覆添加的镍包WC含量为10％、30％、50％的铁基合金涂层的组织演变过程和WC含量变化对涂层相的影响,分析了各相的析出规律,并将计算结果与试验结果进行了分析与比较,得出计算结果与试验结果基本吻合．该研究为进一步挖掘涂层组织潜力和改善熔覆工艺提供了理论依据．     

不锈钢等离子熔覆镍基复合涂层的组织与性能

利用等离子熔覆技术,在304不锈钢基体上制备了添加WC颗粒的镍基复合涂层。借助SEM、EDS、XRD分析了涂层的组织,采用显微硬度计、M-200磨损试验机和电化学工作站分别测试了涂层的硬度和耐磨、耐蚀性能。实验结果表明,涂层呈枝晶生长特征,组织均匀细小,主要由γ-(Ni,Fe)固溶体、Cr_(23)C_6、CrSi_2、WC和M6C组成。涂层的显微硬度可达420~530HV0.3,与基体相比,涂层磨损性能提高4倍以上;在3.5%NaCl介质中涂层耐蚀性优于304不锈钢。     

等离子喷涂参数对镍基合金涂层组织及冲蚀磨损性能的影响

采用SEM、XRD、LSCM和冲蚀磨损试验机研究了等离子喷涂参数(氢气流量HFR、喷涂电流I)对Ni60涂层组织与冲蚀磨损性能的影响。结果表明,Ni60涂层主要由γ-Ni、Ni3B、Cr2B、CrB、M7C3、M23C6相构成;增加HFR、I有利于减小涂层中层片厚度,增加涂层结晶度、平均晶粒尺寸、微观应变量及残余应力,提高涂层显微硬度及抗冲蚀磨损性能。但过大的HFR、I(15ft3/h、600A)导致涂层孔隙率增加,显微硬度及抗冲蚀磨损性能降低。等离子喷涂参数HFR=12.5ft3/h、I=500A时,在小角度冲蚀条件下,Ni60涂层具有更高的抗冲蚀磨损性能。     

热喷涂涂层与电镀层的结合与界面

为提高热喷涂涂层与电铸层间的结合强度,分别选用QAl9-2、Ni95Al5和0Cr25Al5等3种自结合材料做过渡层,沉积在电弧喷涂3Cr13涂层与电铸Ni层之间.结果表明,Ni95Al5过渡层的效果最好,可提高涂层体系结合强度至少一倍,QAl9-2与0Cr25Al5过渡层的效果次之.借助于扫描电子显微镜,分析了热喷涂涂层与电铸层界面的微观组织,研究了过渡层的强化机制.在该涂层体系中,自结合涂层与电铸镍层发生冶金结合,自结合涂层的自由表面为后续沉积的3Cr13涂层提供了极好的机械结合界面,保证了涂层体系的可靠结合.     

Microstructure of Ni / WC surface composite layer on gray iron substrate

The surface infiltrated composite (Ni/WC) layers on gray iron substrate were fabricated through a vacuum infiltration casting technique (VICT) using Ni-based composite powder with different WC particles content as raw materials.The microstructures of surface infiltrated composite layer,the interface structures between surface composite layer and the substrate,the changes of macro-hardness with the increasing of WC content and the micro-hardness distribution are investigated.The infiltrated composite layer includes a surface composite layer and a transition layer,and the thickness of the transition layer decreases with the increasing content of WC.The thickness of transition layer with 20%WC content in the surface infiltrated composite layer was 170 μm which was the thickest for all transition layers with different WC content.The surface composite layer was mainly composed of WC,W2C,FeB and NiB,along with Ni-Cr-Fe,Ni (Cr) solid solution,Ni (Si) solid solution and Ni (Fe) solid solution.The transition layer was composed of Ni (Cr) solid solution,Ni (Fe) solid solution,Ni (Si) solid solution,Fe (Ni) solid solution and eutectic.The surface macro-hardness and micro-hardness of the infiltrated layer had been evaluated.The macro-hardness of the surface composite layer decreases with the WC content increasing,and the average macro-hardness is HRC60.The distribution of micro-hardness presents gradient change.The average micro-hardness of the infiltrated layer is about HV1000.     

Abrasive wear behaviors of high velocity arc sprayed iron aluminum composite coatings

The High Velocity Arc Spraying （HVAS） technology was used to prepare Fe-Al composite coatings by the adding of different elements into cored wires to obtain different Fe-Al coatings. The added compounds do great effect on the properties of the composite coatings. The microstructures and abrasive wear performances of the coatings were assessed by transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, and THT07-135 high temperature wear equipment. It was found that the adding of Cr3C2 can greatly increase the room temperature wear behavior, and Fe-Al/WC coatings have adapting periods at the beginning of wear experiment. With the rise of temperature, the wear resistance of Fe-AI/Cr3C2 coatings becomes bad from room temperature to 250℃, and then stable from 250℃ to 550℃; the wear resistance of Fe-Al/WC becomes well with the rise of temperature. The adding of Cr and Ni can also improve wear performances of Fe-Al composite coatings.     

激光熔覆Ni+Cr_2O_3复合涂层的耐蚀性

研究了激光搭接熔覆Ni+Cr2 O3复合涂层在 0 .5mol/LH2 SO4 +0 .5mol/LNaCl水溶液中的电化学行为 .试验表明Cr2 O3粒子在激光熔池中发生了完全溶解 ,涂层具有胞状枝晶组织特征 .激光熔覆Ni+Cr2 O3复合涂层比单一熔覆Ni合金涂层和 2Cr13马氏体不锈钢基材具有更低的维钝电流密度和更宽的钝化区范围 ,明显改善了在该腐蚀介质中的抗点蚀能力 .     

等离子喷焊层NiCrBSi+WC/Co的组织与性能

利用等离子喷焊技术在H13模具钢表面制备NiCrBSi+20%WC/Co喷焊层。研究表明,基体与喷焊层之间存在明显的分界面,与传统焊接接头的微观组织类似,喷焊层中出现垂直于界面结合方向的柱状晶,这种组织形态在等离子喷涂涂层中从未观察到,说明喷焊层NiCrBSi+20%WC/Co与H13钢基体之间的结合为冶金结合。XRD分析表明,喷焊层中的主要相为γ-(Fe,Ni),Cr7BC4,Ni4B3,Cr7C3和Co7W6,并且由于这些相的存在,使得表面喷焊层比H13钢基体具有更高的强度和硬度。     

冷作模具钢激光熔覆Ni基合金组织和性能研究

为提高Cr12MoV模具钢硬度和耐磨性,研究采用激光熔覆技术在其表面制备Ni基合金。研究结果表明,涂层显微组织为异向生长的树枝晶,涂层相结构为γ-(Fe,Ni)、Cr7C3、BNi2以及Ni-Cr-Fe相。由于细晶强化、固溶强化和第二相强化作用,使熔覆层平均硬度比基体硬度提高了175%。涂层摩擦系数为0.2,明显小于基体（0.5）,涂层的磨损体积较基体提高1个数量级。     

Microcrystalline coatings deposited by series double-pole electro-pulse discharge and its high-temperature oxidation behavior

A new technique——series electro-pulse discharge (SEPD)——was developed as asurface coating process. In this process, both positive and negative poles of a pulse power were used as the depositing electrodes and the substrate alloy was used as an induction electrode. The physical process for such SEPD was tested by measuring the relationship between the discharge voltages and gaps in a pin-plate-pin system. Microcrystalline Ni20Cr alloy coatings and oxide-dispersed Ni20Cr alloy coatings were prepared on Ni20Cr alloy surface by using a vibrating SEPD device. Oxidation at 950℃ in ambient air showed that the microcrystalline Ni20Cr alloy coatings greatly improved the oxidation resistance of the substrate alloy. The addition of dispersed Y2O3 nano-particles into the microcrystalline coatings was found to further reduce the oxidation rate and enhance the oxide spallation resistance.     

Preparation of Ni60-WC coating by plasma spraying, plasma re-melting and plasma spray welding on surface of hot forging die

In order to produce the hear-resistant inner layer of hot-forging die, the plasma spraying and plasma re-melting and plasma spray welding were adopted. Substrate material was W6Mo5Cr4V2, including 10%, 20%, 30% tungsten carbide (WC) ceramic powder used as coating material to obtain different Nickel-based WC alloys coating. Micro-structure and micro-hardness analysis of the coating layer are conducted, as well as thermophysical properties for the coating layer were measured. The experimental results show that the coating prepared with 70%Ni60, 30%WC powder has the best properties with plasma spray welding, in which the micro-hardness can achieve 900HV, meanwhile it can improve the thermal property of hot-forging die dramatically.