电火花沉积Ni-Cr合金涂层的组织及性能

利用电火花沉积技术,采用自制电极在P20钢基材表面沉积Ni-Cr合金涂层,研究了沉积层的组织特征、显微硬度分布及耐磨、耐蚀性能。结果表明:通过优化沉积工艺参数可以获得厚度高达430μm的沉积层。电火花沉积层与基体的结合界面属于非均匀混合互熔结晶型界面,沉积层与基体呈现良好的冶金结合;涂层中下部组织为细小的枝晶组织,而上部组织为纳米晶结构。沉积层的硬度呈梯度分布,涂层外层硬度值最高。涂层的耐磨、耐蚀性能比基体有较大提高,涂层上部超细的纳米晶结构是其耐磨性能及耐蚀性能提高的主要因素。     

激光沉积制备钛基梯度耐磨涂层组织和性能研究

为了提高Ti6Al4V钛合金的高温耐磨特性,在Ti6Al4V钛合金表面利用激光沉积制造原位生成TiC颗粒增强相的方法制备了钛基梯度涂层。观察了耐磨梯度涂层的微观组织,测量了涂层和Ti6Al4V基材在500℃条件下的摩擦磨损性能及其显微硬度,并对涂层的强化机制和磨损机理进行了分析。结果表明,原位自生的TiC颗粒增强相均匀弥散分布在基体中,从基材到涂层顶部分别呈现粗大树枝晶、较大的颗粒状晶体、相对细小的颗粒状晶体形态。显微硬度分析显示涂层硬度保持在400～450HV之间,由基材到表层呈梯度上升趋势。涂层表现出较好的高温耐磨特性,和基材的磨损体积比为2.86。TiC颗粒的弥散分布强化和激光沉积基体组织的细晶强化是显微硬度和高温耐磨性提高的主要原因。     

激光熔覆Fe60Nb20Ti20非晶合金粉末及组织性能研究

采用激光熔覆工艺在45钢表面对Fe60Nb20Ti20非晶合金粉末进行不同工艺参数熔覆试验,获得无裂纹且呈冶金结合的涂层。利用扫描电镜、X射线衍射仪、显微硬度计、摩擦磨损试验机对涂层的微观形貌、组成相、显微硬度和摩擦磨损性能进行分析。结果表明,涂层组织为细小的α-Fe过饱和固溶体等轴晶和少量的非晶相。涂层平均硬度为857HV,为基体材料的4倍,耐磨性也明显优于基体材料。     

工艺参数对304不锈钢表面激光熔覆Ni基合金涂层的组织、耐磨性及耐腐蚀性的影响

研究了不同工艺参数对304不锈钢表面激光熔覆Ni基合金后熔覆层微观组织及硬度、耐磨、耐蚀性能的影响,并寻求最佳激光工艺参数,以期获得冶金结合较好,耐磨、耐蚀性能良好的熔覆层。根据组织与性能的综合分析可知,最优激光工艺参数为激光功率2.5kW、扫描速度4mm/s、送粉速率300mg/s。利用优化工艺参数熔覆后的熔覆层宏观形貌平整、光滑,熔覆层宽度为14.36mm,高度为1.612mm,熔池深度为0.248mm,稀释率为13.33,硬度较高,平均显微硬度为646.4HV,并且耐磨损性能较好,磨损量较低。此外,熔覆层的耐腐蚀性能也较好,自腐蚀电位为-286.77mV。在一定的激光工艺参数下,组织从结合区至熔覆层表层依次为平面晶、胞状晶、柱状晶、树枝晶、等轴晶。激光功率、扫描速度、送粉速率不同,熔覆层中组织粗细变化呈现一定的规律性:随着激光功率的增大,组织由细小逐渐变的粗大;随着扫描速度的增大,组织先变细小,然后变粗大;随着送粉速率的增大,组织逐渐变细小。合金的耐磨性与耐蚀性不仅与组织大小有关,而且与组织物相组成密切相关。     

WC量对发动机用Ti600表面激光熔覆Ni60A涂层性能的影响

在Ni60A粉末内加入10%、20%与30%不同质量分数WC颗粒,利用激光熔覆方法在发动机用Ti600基底表面形成Ni60A/WC涂层,通过实验测试手段分析WC量对涂层组织及性能的影响。研究结果表明:形成了具有同样成分的Ni60A涂层,析出了等轴晶、长条形、环状组织。在Ni60A涂层内加入20%的WC之后,获得了更致密的Ni60A涂层,表现为明显的网篮型组织形态,此时形成了许多细小的TiC晶粒,并且TiB比例大幅提高。加入WC情况下,形成的Ni60A涂层硬度明显增加。加入30%Ni60A/WC后,获得了最大硬度的Ni60A涂层,与基底相比提高了近2倍。由此表明,Ni60A涂层相对于基底组织发生了硬度的大幅提高。加入WC后,摩擦系数减小到0.6以内,磨损量减小到1.0 mg以内,表明Ni60A/WC可以发挥良好减摩效果。在试样表面形成了许多鱼鳞外形的碎屑,加入Ni60A/WC后可以使Ni60A涂层获得更强的耐磨能力。     

激光熔覆马氏体不锈钢组织与性能分析

对马氏体不锈钢添加不同含量的Nb、Ti合金元素,通过高速激光熔覆在316L不锈钢基体上制备出不同合金成分的涂层,对比分析了不同合金涂层的组织和性能变化。试验结果表明:激光熔覆马氏体不锈钢组织以树枝状的马氏体组织为主,Ti和Nb元素促进树枝晶组织向等轴晶转变,Ti元素对熔覆质量和等轴晶的促进作用更明显。     

等离子束熔覆铁基合金涂层的组织与性能研究

利用等离子熔覆技术,在钢基体表面熔覆了一层铁基合金,获得了与基体呈冶金结合的、性能良好的涂层;采用金相显微镜对熔覆层的组织进行观察,发现熔覆层整体组织由柱状树枝晶向等轴晶转变,无气孔、夹杂,其中枝晶组织粗大,等轴晶组织细小;利用显微硬度计分析表明,熔覆层具有较高的硬度,并且由表面到基体呈梯度分布;磨损试验结果表明熔覆层的耐磨性是淬火45钢的2.56倍.     

TA15钛合金表面原位合成TiC增强钛基激光熔覆层的组织与耐磨性EI北大核心CSCD

采用激光熔覆技术在TA15钛合金表面原位合成TiC增强钛基涂层。利用光学显微镜、扫描电镜、X射线衍射仪、能谱分析仪、显微硬度计、摩擦磨损试验机等研究涂层的成形质量、微观组织、物相组成、硬度和摩擦学性能。结果表明:涂层主要由β-Ti,Co_(3)Ti,CrTi_(4)和TiC等物相组成,涂层与基体形成了良好的冶金结合。涂层结合区组织是平面晶和柱状晶,中部组织是树枝晶,顶部组织是等轴晶。涂层各微区的碳化钛形貌有显著差别,其中顶部和中部区域碳化钛为粗大的树枝状和花瓣状,而结合区为针状和近球状。涂层显微硬度最大值为715HV,约是TA15显微硬度(330HV)的2.1倍;同等条件下涂层磨损量为30.14 mg,约为TA15磨损量98.11 mg的30.7%。涂层与基体的磨损机制均为磨粒磨损和黏着磨损的复合磨损模式,但涂层的磨损程度较轻。     

TA15表面激光熔覆镍基和钴基涂层组织和性能对比研究

本工作探究了钛合金TA15表面激光熔覆镍基和钴基合金对涂层摩擦磨损性能的影响.采用2 kW光纤激光器,在TA15表面分别制备了Ni60A-50％Cr3 C2-1.0％Y2 O3和Stellite6-5％TA15-2.5％Y2 O3复合涂层,利用SEM、EDS和XRD分析涂层的组织和物相,利用显微硬度计测量涂层的硬度,利用MMG-500三体磨损试验机进行摩擦磨损试验.两种涂层和基体均呈良好的冶金结合,镍基涂层主要由 γ-(Fe,Ni)、TiC和Cr3 C2等相组成,钴基涂层主要由γ-Co、TiC、Co3 Ti和Cr5 Si3等相组成.镍基涂层结合区组织是平面晶和柱状晶,涂层中部组织是树枝晶和枝晶间的共晶组织,涂层顶部是等轴晶.而钴基涂层结合区组织是平面晶、柱状晶和块状晶,涂层中部是棒状组织和树枝晶,涂层顶部是等轴晶.镍基和钴基涂层显微硬度分别为1209HV0.2和1072HV0.2,约为TA15显微硬度(330HV0.2)的3.7倍和3.2倍.两种涂层的耐磨损性能均显著提高,但镍基涂层的耐磨效果比钴基涂层更好.     

铝青铜表面激光熔覆镍基涂层的组织与磨损性能

为了改善铜合金表面的耐磨性能,利用超音速火焰喷涂和激光重熔技术在铝青铜上制备了镍基涂层。分析了激光熔覆层的微观组织,测试了其显微硬度及磨损性能。结果表明:熔覆层组织致密、无裂纹,与铝青铜形成了良好的冶金结合;从熔覆层表层到基体热影响区,组织呈现出由细小的柱状晶→胞状晶、树枝晶→平面晶过渡;激光熔覆层磨损量约为铝青铜的1/4,熔覆层耐磨能力的增强归因于熔覆层与铝青铜间良好的冶金结合及基体与涂层元素固溶强化和碳化物等析出相的强化作用。     

45钢表面激光熔覆CoCrNi中熵合金涂层组织与性能

为探究CoCrNi中熵合金在激光熔覆领域中的应用,以CoCrNi合金粉末作为熔覆粉末,在45钢表面采用同轴送粉法制备合金涂层。利用扫描电镜、X射线衍射仪、显微硬度仪、摩擦磨损实验机和电化学工作站等设备研究了熔覆层微观组织、硬度、耐磨性和耐腐蚀性能。结果表明：熔覆层成形良好,组织均匀致密,组成相主要为FCC单相固溶体;熔池与基体交界处为平面晶,底部靠近中心为柱状晶,顶部分别为胞状晶和等轴晶,3种元素在熔覆层深度方向上的比例几乎相同;熔覆层平均硬度为250HV,摩擦系数、磨损量较基体分别降低了11.7%和36.7%;自腐蚀电流密度略有降低,CoCrNi熔覆层的钝化区域为-150到1 100 mV,表明熔覆层显著提高45钢的耐腐蚀性能。     

304不锈钢激光原位合成自润滑涂层的宽温域摩擦学性能

由于304不锈钢在中、高温下摩擦学性能较差,制约了其在重要摩擦运动副零部件上的应用。为改善304不锈钢的摩擦学性能,以Ni60粉末为增韧相,WS2为合成润滑相的前驱化合物,TiC为高硬度耐磨相,采用高能激光束在其表面原位合成自润滑耐磨复合涂层。利用X射线衍射仪、扫描电子显微镜、显微硬度计、摩擦磨损试验机和探针式材料表面磨痕测量仪表征涂层和基体的物相、微观结构、显微硬度与表面形貌,并系统研究涂层和基体在20,300,600,800℃下的摩擦学性能及其磨损机理。结果表明:涂层主要由Cr0.19Fe0.7Ni0.11,Ti2SC,Fe2C,Cr7C3,CrS和WS2组成;涂层的平均显微硬度(302.0HV0.5)略高于基体(257.2HV0.5),但涂层上部区域的硬度(425.4HV0.5)约为基体的1.65倍;涂层在所有等温摩擦学实验中摩擦因数和磨损率均低于基体,300℃时涂层润滑效果最好,摩擦因数为0.3031,600℃时涂层耐磨效果最好,磨损率为9.699×10^-5 mm^3·N^-1·m^-1。     

Improvement of wear resistance behaviour of laser metal deposited Ti6Al4V/Mo composites

Titanium and its alloys are materials found to exhibit wonderful properties such as its lightweight and, excellent mechanical properties – tensile strength and toughness even at elevated temperatures, extraordinary corrosion resistance behaviour and ability to withstand high temperatures. These unique properties have made Ti6Al4V attractive for a range of industrial applications. Some of the successful applications include medical implants and prosthesis, connecting rods for automotive, aerospace, oil and gas, sports equipment, gas turbine engines and space crafts. However, the high cost and poor wear resistance of Ti6Al4V limits its use for specific applications. This study investigates the wear resistance of the laser deposited Ti6Al4V composite and its enhancement with molybdenum. In this study, the Ti6Al4V/Mo composites were produced, the effect of influencing process parameter was investigated, and the produced Ti6Al4V‐Mo composites were further examined through various tests. The results revealed that the Ti6Al4V/Mo composite produced at varying laser powers had improved wear resistant when compared to the Ti6Al4V substrate. A direct correlation between the wear resistance and hardness was also observed.     

钛表面激光熔覆原位制备Ti5Si3涂层结构及摩擦学性能

利用激光熔覆技术在钛表面预置硅粉原位制备了Ti5Si3涂层.用XRD、SEM和TEM分析了涂层的组成和组织结构.在UMT摩擦磨损试验机上对Ti5Si3涂层在不同载荷和不同滑动速度下的摩擦磨损性能进行了测试.实验结果表明:涂层的物相主要是Ti5Si3相和基材Ti相,涂层的显微结构为球状和块状晶,Ti5Si3涂层具有较高的显微硬度,涂层截面的平均显微硬度约为840 HV0.2,是钛基材的4.4倍;Ti5Si3涂层可显著提高钛基材的耐磨性能;Ti5Si3涂层的磨损机理为磨粒磨损和粘着磨损.     

Corrosion behaviour of some vapour deposited magnesium alloys

Abstract

Binary magnesium alloys containing chromium, manganese, or titanium were made using a physical vapour deposition technique. The corrosion resistance of the alloys was assessed in aqueous chloride solutions using total immersion tests in quiescent 600 mmol L^?1 NaCI solutions. Alloying with manganese or titanium was found to lower the corrosion rate of magnesium over most of the compositional ranges of interest, whereas addition of chromium had a detrimental effect on the corrosion resistance of magnesium. The lowest corrosion rate was recorded for a Mg–Ti alloy where the value obtained was about 80 times lower than that found for vapour deposited pure magnesium. Open circuit corrosion potential measurements conducted in 600 mmol L^?1 NaCl solution showed that additions of chromium, titanium, and manganese also produced deposits which were significantly more noble than pure magnesium, suggesting that these alloys would be less susceptible to galvanic corrosion.

MST/3064     

Ti6Al4V钛合金表面Ta2O5/Ta2O5-Ti/Ti多涂层的制备与性能研究

采用磁控溅射技术在Ti6Al4V钛合金表面制备了Ta_2O_5/Ta_2O_5-Ti/Ti多层涂层;利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和X射线光电子能谱仪 (XPS),分析了涂层的微观结构、物性组成和化学价态;通过划痕仪、纳米压痕仪、摩擦磨损试验机和电化学工作站,检测了涂层的结合强度、力学性能、摩擦系数和耐腐蚀性。研究结果表明,Ta_2O_5/Ta_2O_5-Ti/Ti多层涂层表面由峰型颗粒组成,粒径大小均匀,涂层结构致密。与Ti6Al4V相比,Ta_2O_5/Ta_2O_5-Ti/Ti多层涂层试样具有较小的摩擦系数,较高的腐蚀电位和较小的腐蚀电流密度,表现出良好的耐磨和耐腐蚀性能,能对Ti6Al4V合金植入材料起到较好的保护作用。     

CoCuFeNiTi高熵合金涂层的制备和性能研究

采用激光熔覆技术在40 Cr钢基材表面制备CoCuFeNiTi高熵合金涂层,使用SEM、XRD和EDS等手段分析涂层的显微组织和相组成,研究了涂层的制备工艺、显微硬度、耐磨损和耐腐蚀性能。结果表明：在激光功率为700 W、扫描速度为6 mm/s条件下制备的CoCuFeNiTi高熵合金涂层表面质量较好,涂层与基体之间形成了良好的冶金结合;这种涂层由FCC相、少量的Cu₄Ti相和微纳级富Cu析出相构成,具有典型的树枝晶显微组织,Cu元素在枝晶间偏聚并形成微纳级富Cu析出相;涂层的显微硬度约为438.83HV,是基体的1.7倍;涂层的磨损质量损失约为基体的1/2,表明这种涂层具有更高的耐磨损性能。涂层的磨损,以黏着磨损为主伴有一定程度的磨粒磨损;这种涂层在pH=4的酸性溶液和3.5%NaCl溶液中的耐蚀性均优于基体。     

Q235低碳钢表面等离子熔覆TiB2-TiC/Fe复合涂层及耐磨性

采用等离子熔覆技术,以Fe55、Ti、B₄C混合粉末为原料,在Q235低碳钢表面获得了TiB₂-TiC/Fe复合涂层,并分析了涂层的物相组成、组织结构,测试了显微硬度和摩擦磨损性能,探讨了其磨损机制。TiB₂-TiC/Fe复合涂层的主要物相为TiB₂、TiC、α-Fe,其中TiB₂呈多边形和矩形,TiC则呈不规则块状;随着原始粉末中Ti、B₄C含量的增加,TiB₂、TiC尺寸逐渐增大,TiB₂-TiC/Fe涂层与基体之间结合紧密,呈冶金结合;随着TiB₂-TiC/Fe复合涂层陶瓷相含量的增加,涂层硬度和耐磨性显著提高,当陶瓷相含量增加到一定程度（35wt%）时,涂层耐磨性能有所降低,TiB₂-TiC/Fe复合涂层的磨损方式主要是磨粒磨损和剥层磨损。Ti+B₄C陶瓷相含量为30wt%的等离子熔覆涂层耐磨性能较好,约为Q235钢基体的7倍,当Ti+B₄C含量持续增加时,TiB₂、TiC尺寸增大、缺陷增多,最终使TiB₂-TiC/Fe复合涂层耐磨性降低。     

(Ti,Cr)N and Ti/TiN PVD coatings on 304 stainless steel substrates: wear-corrosion behaviour

When hard nitrides coatings work in aggressive environments, wear phenomena occur in conjunction with corrosion processes; hence the characterisation of wear and corrosion resistance, considered as two distinct aspects, cannot be regarded as representative of the real degradation process, where the interactions between the two phenomena become extremely important. In this work wear-corrosion tests were performed by means of a laboratory-made apparatus, where the electrochemical characterization can be easily carried out. TiN coatings (with and without the presence of a Ti underlayer) and (Ti,Cr)N coatings were tested under different wear conditions in a sodium chloride solution. The results were compared and the different behaviour was interpreted in terms of film texture and residual stresses due to the PVD process. The (Ti,Cr)N deposits, which have the best intrinsic corrosion resistance, turned out to be the less resistant coatings to the wear-corrosion process, probably because residual stress was much higher than in TiN, making the coating more brittle and poorly adherent to the substrate. The TiN/Ti samples showed the best behaviour under wear-corrosion, which can be explained by a better adhesion of the coating, enhanced by the titanium underlayer. Moreover, the presence of the Ti underlayer proved to be effective in reducing the residual stresses in the TiN layer.     

Maßgeschneiderte Schicht-Interfacesysteme mittels ionenstrahlgestützter Beschichtung

Custom-Tailored Coating-Interface Systems by Means of lon Beam Assisted Deposition A coated sample represents in its most simple form a threefold junction consisting of substrate interface and top layer. In many cases the top layer consists again of several sublayers or the interface contains a modified substrate surface and an interconnection between top layer and interface. An ideal coating technique is evaporation under simultaneous ion bombardment with an ion source it is possible because of several free parameters to come close to an ideal system. For the coating Al/Al₂O₃ on steel it is shown that the width of a composition gradient between the sublayers Al and Al₂O₃ can be optimized with respect to excellent corrosion resistance. The example Cr_xN coating on steel or corrosion and wear resistence demonstrate the ability to optimize the corrosion and wear resistence by modifying the microstructure via variation of the parameters ion energy, ion impact angle, ion to atom ratio and process temperature. Finally, TiN layers on steel were chosen to show that the ion beam parameters influence the porosity and the crystal structure of the coatings. This fact can be used to optimize the corrosion protection or wear reduction obtained by the coating. Especially the multilayer Ti/TiO₂/TiN exhibits very interesting properties.