Effects of pulse current on properties of electrodeposited RE-Ni-W-P-SiC composite coating

Effects of pulse current on properties of electrodeposited RE-Ni-W-P-SiC composite coating were studied. The results show that hardness of the pulse current electrodeposited composite coatings is higher than that of the direct current electrodeposited composite coatings while other parameters are the same. Otherwise, the deposited velocity is higher, and wear resistance and corrosion resistance of the pulse current electrodeposited composite coatings are also improved when the average current density is 10 A/dm2 , pulse frequency is 800 Hz and duty ratio is 1: 5. The hardness of the coating as-deposited is HV500 - 700, and it reaches HV1300 after heat treatment at 400 ℃ for 1 h.     

不同粒径的Ni-W-P/Al_2O_3复合镀层耐磨性能研究

用化学镀的方法制备了几种不同粒径的Ni_W_P/Al2O3复合镀层,研究了热处理温度对镀层硬度和磨损性能的影响,并将含有50 nm、500 nm、1~3μmAl2O3粒径的复合镀层进行了性能对比。结果表明:含有50 nmAl2O3粒径的复合镀层具有更高的硬度和耐磨性,经400℃处理后的镀层耐磨性最好。     

CATHODIC PROCESS AND WEAR RESISTANCE OF ELECTRO-DEPOSITED RE-Ni-W-P-SiC COMPOSITE COATING

Cathodic deposition current density of the composite coatings increases when SiC par-ticles and rare earth (RE) were added in the bath, which is profitable for Ni- W-P alloy to deposit in the cathod, forming Ni-W-P-SiC and RE-Ni-W-P-SiC composite coatings. On the contrary, the addition of PTFE in the bath decreases cathodic deposition current density of the coatings. The current density increases a little when the amount of RE isγ-9g/l; however, the current density increases greatly when the amount of RE is increased to 11-13g/l. But if the amount of RE is raised further, the current density decreases. Hardness and wear resistance of RE-Ni-W-P-SiC composite coating have been studied, and the results show that the hardness and wear resistance of RE-Ni-W-P-SiC composite coating increase with increasing heat treatment tempera-ture, which reach peak values at 400℃; while the hardness and wear resistance of the coating decrease with the rise of heat treated temperature continuously.     

PROPERTIES OF ELECTRODEPOSITED AMORPHOUS Ni-W-P-SiC COMPOSITE COATINGS

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Microstructure and Wear Resistance Evolution of HVOFSprayed WC-（W,Cr）2C-Ni Coating with Post Heat Treatment In Air Atmosphere

WC-(W,Cr)2C-Ni coating was prepared on 1Cr18Ni9Ti stainless steel and C-276 Ni-base Hastelloy by high velocity oxy-fuel(HVOF)spraying.The effect of post heat treatment in air atmosphere on the microstructure,phase composition,microhardness,fracture toughness,and wear resistance of HVOF-sprayed WC-(W,Cr)2C-Ni coating was investigated.The microstructure and phase composition of the coatings were analyzed by means of field emission scanning electron microscopy(FESEM)and X-ray diffraction(XRD).The microhardness and fracture toughness of the coatings were measured using a microhardness tester and a Vickers hardness tester.Moreover,dry friction and wear behavior of the coatings sliding against Si3N4 ball was investigated using an oscillating friction and wear tester;and the worn surfaces of the coatings were analyzed by means of scanning electron microscopy(SEM).It was found that heat treatment within 500-800°C resulted in crystallization of amorphous phase in as-sprayed coating,generating nanoscale new phases such as NiWO4,CrWO4 and Cr2WO6.Besides,heat treatment led to increase of the microhardness of as-sprayed coating,and the highest microhardness was obtained after heat treatment at 800°C.The fracture toughness and wear resistance of the as-sprayed coating increased with increasing heat treatment temperature up to 700°C but tended to decrease with further elevating temperature.In other words,the mechanical properties and wear resistance of the as-sprayed coatings were worsened owing to excessive growth of oxidation grains and depletion of ductile Ni binder after heat treatment above 700°C.Thus it was suggested that as-sprayed ceramic composite coating should be post heat treated in air at a moderate temperature of 700°C so as to achieve the optimized mechanical properties and wear resistance.     

氮碳氧复合处理(QPQ)对MPS700A钢组织与性能的影响

采用氮碳氧复合处理(QPQ)技术对耐蚀耐热不锈钢MPS700A钢进行表面改性,分别进行(450～500) ℃×5 h和(550～570) ℃×3 h盐浴氮碳共渗试验,氧化处理工艺均为400 ℃×30 min。对QPQ处理后试样渗层的表面形貌、表面硬度、脆性及其耐磨性进行了分析。结果表明:渗层主要由氧化膜层、疏松层、化合物层和扩散层构成,QPQ处理后试样的硬度明显提高,相对低温段490 ℃盐浴氮碳共渗试样的硬度最高,相对高温段550 ℃处理的试样硬度最高,分别为1295、1344 HV0.1,分别是基体硬度的3.75和3.90倍。QPQ处理试样的渗层组织细小,均匀致密,脆性低,耐磨性好,比祼钢具有较好的高温摩擦磨损性能,尤其在500 ℃以上性能更加优异。且与550 ℃盐浴氮碳共渗QPQ试样相比,490 ℃盐浴氮碳共渗QPQ试样具有更低的脆性,更好的高温摩擦磨损性能。     

Ni/Al2O3复合镀层中Al2O3微粒尺寸及热处理对镀层性能的影响

目的强化Ni基镀层并确定Al_2O_3尺寸对复合镀层性能的影响。方法在以硬度为评价标准的最佳工艺条件下,制备了三种尺寸的Al2O3(微米级、50 nm、30 nm)复合镀层,研究分析了不同尺寸Al_2O_3复合镀层的表面形貌、显微硬度、耐磨、耐蚀等性能。结果纳米复合镀层的表面形貌比微米复合镀层更光滑、平整、致密,晶粒更细小。Al_2O_3微粒尺寸越小,镀层越致密。纳米复合镀层的显微硬度、耐磨性能、耐蚀性能、抗高温氧化等性能均优于微米复合镀层及纯Ni镀层。热处理后的纳米复合镀层表面更加平整致密,热处理能显著提高镀层的显微硬度。50 nm复合镀层在保温温度为400℃时达显微硬度最大值461HV,30 nm复合镀层在保温温度为500℃时达显微硬度最大值496HV。热处理对纳米复合镀层的耐磨性能改善不明显。结论 Al_2O_3的尺寸越小,复合镀层的性能越好。     

Ni/P金刚石化学复合镀层性能与组织研究

本文研究了金刚石含量、热处理温度、表面活性剂种类等因素对Ni-P-金刚石复合镀层的显微硬度与耐磨性能的影响;采用扫描电子显微镜、X射线衍射仪对复合镀层的表面形貌及组织结构进行了分析。结果表明:在化学镀层中共沉积金刚石微粉能显著提高镀层的耐磨性;各工艺因素对复合镀层显微硬度与耐磨性的影响程度各不相同,热处理温度对复合镀层耐磨性能的影响最大;当镀液中金刚石微粉含量为2 g/L、热处理温度400℃、表面活性剂为SHP其含量为1∶15时,复合镀层的耐磨性能最好。与Ni-P化学镀层相比,金刚石复合镀层的耐磨性提高50%。     

热处理温度对AZ91D合金表面Ni-P-SiC复合镀层性能的影响

目的提高镁合金表面Ni-P-SiC复合镀层的耐腐蚀性能和耐磨性能。方法采用加入SiC微粒的Ni-P化学镀溶液,在AZ91D镁合金表面制备Ni-P-SiC复合镀层,并在不同温度下进行热处理,通过X射线衍射(XRD)、显微硬度测试、电化学腐蚀测试和摩擦磨损实验等方法分析和评价镀层的组织构成、显微硬度、耐腐蚀性能和耐磨性能。结果 Ni-P-SiC复合镀层经320℃热处理后,组织结构由非晶向晶体转变,并伴随有Ni3P相的析出。此温度下热处理的Ni-P-SiC复合镀层:显微硬度最高,可达1120HV,为未热处理时显微硬度(620HV)的1.81倍;自腐蚀电位为–0.697 V,较未热处理样品的(–0.727 V)有所提高;腐蚀电流密度基本最小,为0.984μA/cm~(–2);磨损体积最小,为0.324×10~(–3) mm~3。340℃热处理的复合镀层则磨损体积最大,为1.43×10~(–3) mm~3。结论在AZ91D镁合金表面制备的Ni-P-SiC复合镀层经过320℃热处理保温1 h后,复合镀层的硬度、耐腐蚀性能和耐磨性能均有所提高。     

Comparison of molybdenizing and NiCrA1Y coating on Ti and Ti-6A1-4V

Two surface treatments, molybdenizing and depositing NiCrAIY coating, were applied to improve the microhardness and the oxidation re-sistance of titanium and Ti-6Al-4V. Coupons were analyzed using optical microscopy (OM), scanning electron microscopy (SEM) with X-ray energy dispersive spectrometer (EDS), and X-ray diffraction (XRD). Vickers hardness and isothermal oxidation tests were carded out to evaluate the effects of these two surface treatments on the microhardness and oxidation resistance of the substrates. The post vacuum heat treatment of the NiCrAlY coating and the molybdenizing parameters were also discussed. It is found that molybdenizing can obviously in-crease the surface hardness of titanium due to the formation of β,α", and α' phases in the diffusion layer. As γ' phase is formed after vacuum heat treatment, the NiCrAIY coating is effective in improving the surface hardness of Ti-6Al-4V. The NiCrAlY coating can obviously de-crease the oxidation rate of Ti-6Al-4V at 700-900℃, which can be attributed to the formation of Al2O3 and Cr2O3 mixed scale during the oxidation.     

Fe-P非晶合金的电沉积行为及热处理对其结构与性能的影响

在以柠檬酸三钠为络合剂的酸性镀液中电沉积Fe-P非晶合金,采用差示扫描量热(DSC)、X射线衍射(XRD)和扫描电镜(SEM)研究该合金镀层的晶化行为和表面微观形貌。结果表明:镀液中加入络合剂,且随着pH值升高和温度降低时,Fe-P非晶合金共沉积的阴极极化增大。镀态Fe-P合金为非晶态结构,于330.5℃时开始晶化;383.6℃时,α-Fe(P)固溶体大量晶化析出;472.5℃时,Fe3P(I-4)相大量脱溶析出。且随着热处理温度升高,合金镀层的耐蚀性能和硬度先增加后下降,450℃热处理所得镀层的耐蚀性能最佳且硬度最大;在400℃以下时,镀膜具有良好的抗热氧化能力,当温度在400℃以上时,抗氧化能力迅速下降。     

热处理对NiCrWB-WC复合涂层组织和性能的影响

采用超音速火焰喷涂技术(HVAF)在铜基体上制备了镍基-碳化钨复合涂层,用X射线衍射仪、光学显微镜、扫描电镜、MM-200型磨损试验机等分析研究了热处理前后涂层的组织结构变化、结合强度、硬度、耐磨性等性能.结果表明,随着热处理温度的提高,涂层中出现新的相组成,涂层与铜基体之间的结合由机械结合转变为冶金结合,涂层硬度和耐磨性有所增加,但两者无明显的线性关系.     

凹凸棒土-CeO2对舰船高温排烟管表面复合镀层组织和抗氧化性能的影响

目的 提高舰船高温排烟管表面的抗氧化性能.方法 采用电沉积和化学镀技术,在舰船高温排烟管用16Mn表面制备纳米复合镀层.通过抗高温氧化性试验,研究凹凸棒土、稀土氧化物CeO2对复合镀层抗氧化性能的影响,并通过扫描电子显微镜和光学显微镜对复合镀层的微观形貌、组织结构进行分析.结果 当镀液中纳米凹凸棒土颗粒的质量浓度小于1.5 g/L时,随凹凸棒土浓度的增加,复合镀层晶粒细化,镀层致密,且随着镀液中纳米CeO2颗粒浓度的增加,镀层表面平整、致密;当镀液中凹凸棒土的质量浓度为0.5 g/L时,氧化增重最小,复合镀层的抗氧化性最好;复合镀层的氧化增重随镀液中的CeO2浓度先降低后增加,当镀液中CeO2的质量浓度为1.5 g/L时,复合镀层的抗氧化性最好.结论 镀液中添加凹凸棒土和纳米CeO2对复合镀层氧化物形貌和抗氧化性产生了明显的影响.     

钢基电镀铝层阳极氧化处理后的组织结构和性能

用扫描电镜（SEM）和X射线衍射分析（XRD）测定了Q235钢上电镀铝层在硫酸溶液中不同时间阳极氧化处理后的组织结构和表面形貌，并对其硬度和耐蚀性能进行了测试。结果表明：电镀铝层经不同时间阳极氧化处理后，表面由非晶态Al2O3相和Al相组成，其上存在有纳米级的孔洞。随着氧化时间的延长，非晶态Al2O3相增多，Al相减少，氧化膜厚度增加，表面孔洞尺寸增大；氧化膜的硬度呈现先增加后降低，最后趋于稳定，且都显著高于电镀铝层的硬度。并且电镀铝层经阳极氧化处理后，在3．5％NaCl溶液中的电化学耐蚀性能大幅度增加，但随着阳极氧化处理时间的延长，电镀铝层的耐蚀性能降低。     

热处理对不锈钢表面化学镀Ni-Cr-P合金镀层结构及性能的影响

采用化学镀工艺在不锈钢表面获得了Ni-Cr-P合金镀层。研究了Ni-Cr-P非晶态合金膜随热处理温度升高,其结构以及显微硬度和耐蚀性的变化规律,并对变化的原因进行了分析。结果表明,镀态Ni-Cr-P为非晶态镀层,200℃热处理开始晶化,到400℃时Ni3P晶化比较完全,800℃时Ni3P完全分解,生成含Ni、Cr、Fe的合金膜的Cr2Ni3和FeNi2P相。其显微硬度随热处理温度升高而升高,500～600℃之间显微硬度略有下降,600～700℃又随着热处理温度的升高而略有升高,700℃后显微硬度略有下降;合金膜的耐腐性在热处理温度200～400℃间变化较小,500℃热处理后其耐腐蚀性下降厉害,600～700℃随着热处理温度的升高其耐腐蚀性又略有升高,800℃后由于Ni3P的分解其耐腐蚀性又急剧下降。     

铁基非晶增强碳化钨涂层的微观结构与性能

采用超音速火焰喷涂技术制备了WC-CoCr/铁基非晶复合涂层。比较研究了复合涂层和WC-CoCr的微观形貌、硬度、耐磨性能、高温氧化性能和腐蚀性能。XRD分析和SEM观察表明,复合涂层主要由WC相、W2C相和铁基非晶相组成。与WC-CoCr涂层相比,复合涂层的硬度有所降低,但是两者没有显著性差异。由于硬度下降,导致复合涂层的耐磨性能略低于WC-CoCr涂层。800℃高温氧化测试表明,复合涂层在800℃具有良好的热稳定性,这归因于氧化过程中生成了一层致密的氧化膜。此外,复合涂层在3.5%氯化钠溶液中的耐腐蚀性能也优于WC-CoCr涂层。     

STRUCTURE AND PROPERTIES OF RE-Ni-B-Al_2O_3 COATING MATERIAL

1.IntroductionItiswellknownthatdiamond,carbide,boride,nitrideandoxidehavehighhardness,lowfrictioncoefficientandgoodwearresistance,yettheiruseislimitedbecauseoftheirlowtensilestrength,weakcapacity0fp0undingandp0ormachinability['].Whileins0lublesolidparticlesareaddedintheelectr0lessbathtoenablethemtoc0dep0sitwithmetals0naplatetoformauniformc0mp0sitelayer,theplatewouldpossessbettercharacteristicsthanthebaremetals0ralloysI2-6].Thestabilizerandactiveagentf0rthebatharedeveloppedbyalot0fexperimentson…     

热处理温度对窄深槽类零件环保铬镀层组织与性能的影响

采用环保三价铬电镀工艺对窄深槽类零件进行电镀铬后,再对铬镀层进行不同温度(0～400℃)的热处理,研究热处理温度对窄深槽类零件环保铬镀层组织和性能的影响,并对热处理前后铬镀层的微观形貌、相结构、显微硬度、结合力和耐磨性进行了分析.结果表明:镀态镀层表面存在微裂纹,经热处理后微裂纹间隙扩大,并且随着温度的升高,镀层结构逐...     

显微组织对4Cr5MoSiV1钢室温和高温耐磨性的影响

采用销盘式高温摩擦磨损试验机,对不同显微组织的4Cr5MoSiV1钢在25℃和400℃下进行了干磨损试验,研究了显微组织对其耐磨性的影响,并探讨了磨损机制。研究结果表明,4Cr5MoSiV1钢在室温下主要为粘着磨损,其耐磨性不仅取决于材料的硬度,还与其断裂抗力有关;400℃时的磨损为氧化磨损,但已超越了Quinn型氧化轻微磨损,其耐磨性取决于材料的硬度、韧性以及热稳定性。室温耐磨组织应具有高的硬度和一定的断裂抗力,而高温耐磨组织应具有高的硬度和热稳定性及一定的韧性。     

热处理对Ni-TiN纳米复合镀层结构和性能的影响

目的进一步提高脉冲-超声电沉积Ni-TiN纳米复合镀层的显微硬度,改善镀层的耐磨性。方法利用扫描电镜、X射线衍射仪、显微硬度计、摩擦磨损仪器,对经200~600℃热处理后Ni-TiN纳米复合镀层的表面形貌、内部组织结构、显微硬度和磨损性能进行检测,研究了热处理方式对复合镀层的表面形貌、晶相组织、显微硬度和耐磨性的影响。结果经300℃保温1.5 h后的镀层表面最为平整和光滑。同时镀层开始实现非晶态向晶态演变,并且镀层硬度最高,其值高达815HV。随热处理温度的升高,镀层晶粒变大,表面平整度降低。经600℃热处理,保温1.5h后,镀层的耐磨性最佳,磨损量仅为13.2 mg。结论经热处理之后,镀层硬度得到一定程度的提高,主要是TiN纳米粒子起到弥散和细晶强化作用。耐磨性得到有效改善,主要是由于镀层韧性、镀层和基体间的结合力得到提高,镀层形成一层致密的氧化膜的原因。