合金镀层对钢冷—热疲劳性能的影响

定性和定量地研究了５种合金镀层对Ａ３钢冷－热疲劳性能的影响，结果表明，其中Ｃｏ－Ｗ镀层的冷－热疲劳抗力最高，Ｎ１－Ｐ，Ｎ１－Ｗ镀层的冷－热疲劳抗力最低，而Ｎ１－Ｃｏ－Ｐ，Ｃｏ－Ｗ－Ｐ居中。     

Co基复合镀层对3Cr2W8V钢热疲劳性能的影响

利用自约束热疲劳试验方法，研究了在３Ｃｒ２Ｗ８Ｖ钢表面上沉积Ｃｏ－Ｃｒ２Ｏ３－，Ｃｏ－Ａｌ２Ｏ３及Ｃｏ－ＣａＦ２复合镀层对钢热疲劳性能的影响。结果表明：Ｃｏ－Ｃｒ２ｏ３及Ｃｏ－ＡｌＯ３复合镀层都在不同程度上提高钢的热疲劳抗力，而Ｃｏ－ＣａＦ２则降低钢的热疲劳抗力。     

热处理对化学沉积Ni-P、Ni-Co-P合金组织及耐蚀性能的影响

研究了热处理对化学沉积Ｎｉ－Ｐ、Ｎｉ－Ｃｏ－Ｐ合金镀层的组织结构、显微硬度、常温静态腐蚀性能和热溶液腐蚀性能的影响。结果表明，Ｎｉ－Ｃｏ－Ｐ合金镀层的显微硬度高于Ｎｉ－Ｐ合金镀层；Ｎｉ－Ｃｏ－Ｐ合金镀层的耐热溶液腐蚀性能及４００℃热处理后的常温静态腐蚀性能均优于Ｎｉ－Ｐ合金。     

电镀

９９０９００１　Ｃｒ镀层、Ｎｉ－Ｐ、Ｎｉ－Ｍｏ、Ｎｉ－Ｗ－Ｐ和Ｍｎ－Ｚｎ合金镀层性能比较——ＡｇｌａｄｚｅＴ．ＴｒａｎｓＩｎｓｔＭｅｔａｌＦｉｎ,１９９７,７５（１）∶３０（英文）研究了Ｃｒ镀层、Ｎｉ－Ｐ、Ｎｉ－Ｍｏ、Ｎｉ－Ｗ－Ｐ和Ｍｎ－Ｚｎ合金镀层性能与电流效率／电流密度比值、热处理前后（对Ｎｉ－Ｐ合金镀层而言）镀层应力和显微硬度的关系。研究了热处理和放电处理对高硬度Ｎｉ－Ｗ－Ｐ合金镀层的影响,用比色分析法分析了各种镀层。详细介绍了电沉积Ｍｎ－Ｚｎ合金［含２５％（ｗｔ）Ｚｎ］的槽液成分、极化曲…     

非晶态Ni－W合金镀层的高温氧化性能研究EI

研究了Ｎｉ－Ｗ合金镀层的抗高温氧化及镀层加热处理后的硬度。为了进一步提高非晶态合金（Ｎｉ－Ｗ）镀层的性能，往镀液中又加入了Ｐ、Ｍｏ、Ｃｅ、Ｂ元素。     

非晶态Ni－W合金镀层的高温氧化性能研究

研究了Ｎｉ－Ｗ合金镀层的抗高温氧化及镀层加热处理后的硬度。为了进一步提高非晶态合金（Ｎｉ－Ｗ）镀层的性能，往镀液中又加入了Ｐ、Ｍｏ、Ｃｅ、Ｂ元素。     

W,P对Ni基非晶镀层耐蚀性能的影响

电沉积Ｎｉ－Ｐ，Ｎｉ－Ｗ和Ｎｉ－Ｗ－Ｐ非晶态合金镀层的阳极化曲线表明，添加类金属Ｐ使镀层的腐蚀电位向正移动，添加高熔点金属Ｗ使维钝电镀密度降低，此外，对Ｎｉ－Ｗ和Ｎｉ－Ｗ－Ｐ合金镀层进行印化处理，可显著提高镀层在ＮａＣｌ溶液中的耐腐蚀性能。     

电沉积RE-Ni-W-P-SiC多功能复合材料的抗高温氧化性研究*

研究了ＲＥ－Ｎｉ－Ｗ－Ｐ－ＳｉＣ多功能复合材料高温氧化性能,结果表明,在高温氧化过程中,纯镍镀层、Ｎｉ－Ｗ－Ｐ、Ｎｉ－Ｗ－Ｐ－ＳｉＣ和ＲＥ－Ｎｉ－Ｗ－Ｐ－ＳｉＣ复合镀层的氧化膜质量和氧化时间的关系呈混合型曲线,即直线和曲线复合的规律。在氧化时间小于６０ｍｉｎ时,氧化膜的增长规律近似于直线方程;而在氧化时间大于６０ｍｉｎ时,氧化膜的增长规律近似于直线方程;而在氧化时间大于６０ｍｉｎ后,它的增长规律可以用幂函数方程表示。４种镀层氧化速率的大小顺序是Ｎｉ〉Ｎｉ－Ｗ－Ｐ〉Ｎｉ－Ｗ－Ｐ－ＳｉＣ〉ＲＥ－Ｎｉ－Ｗ－Ｐ－ＳｉＣ。Ｎｉ－Ｗ－Ｐ、Ｎｉ－Ｗ－Ｐ－ＳｉＣ和ＲＥ－Ｎｉ－Ｗ－Ｐ３种镀层的氧化膜质量随着氧化温度的升高而呈指数型增加。ＲＥ－Ｎｉ－Ｗ－Ｐ－ＳｉＣ复合镀层与Ｎｉ－Ｗ－Ｐ合金层相比,它的高温抗氧化性能可以提高２～３倍     

化学镀镍钴磷合金

对化学镀三元合金Ｎｉ－Ｃｏ－Ｐ镀层的材料性进行了研究，特别对Ｎｉ－Ｃｏ－Ｐ在元合金化学镀层的初期沉积行为及金相结构等进行了探讨，并讨论了磷含量对镀层的影响。     

耐热疲劳性镀层的研究

经过对几种耐热劳性镀层对比试验，发现Ｃｏ－Ｗ镀层具有突出的耐热疲劳性，适合作模具表面镀层。开发出一种电流效率高的Ｃｏ－Ｗ电镀工艺，获得了Ｃｏ含量６３．５％、Ｗ含量３６．５％、与模具钢结合良好、耐热疲劳性好的镀层。并对镀层进行了微观分析。     

n-Al2O3/Ni复合电刷镀层的接触疲劳行为

为研究纳米颗粒复合电刷镀层的接触疲劳行为,通过在镍盐溶液中加入纳米氧化铝(n-Al2O3)颗粒,采用电刷镀技术制备了含n-Al2O3颗粒的镍基复合镀层(n-Al2O3/Ni),采用接触疲劳试验机评价了镀态和热处理态的n-Al2O3/Ni复合镀层的抗接触疲劳性能,并与纯镍刷镀层进行了性能对比.借助SEM和TEM对复合刷镀层的组织进行了分析,探讨了复合刷镀层的接触疲劳失效过程以及纳米颗粒等对刷镀层疲劳失效过程的影响.研究表明:n-Al2O3/Ni复合镀层在镀态下的接触疲劳寿命超过100万周次,明显高于纯镍镀层;退火后n-Al2O3/Ni复合镀层接触疲劳寿命为45.9万次,为纯镍镀层的1.62倍;复合镀层的接触疲劳失效过程分为裂纹萌生、裂纹扩展和镀层断裂3个阶段;纳米颗粒在复合镀层接触疲劳失效过程中起到阻碍位错滑移的作用,从而抑制塑性变形和裂纹扩展,使复合镀层具有较高的接触疲劳寿命.     

TiN气相沉积层对3Cr2W8V钢热疲劳性能的影响

采用自约束热劳试验方法研究了ＴｉＮ等离子气相沉积怪对３Ｃｒ２Ｗ８Ｖ钢热疲劳性能的影响。结果表明：ＴｉＮ沉积层可以有效地提高钢的疲劳抗力，随沉积层厚度减薄，热疲劳抗力增加；随热循环上限温度和蔼同，ＴｉＮ沉积层的热疲劳抗力降低；ＴｉＮ沉积层具有很的热循环稳定及抗氧化性。     

Study of Thermal Fatigue Resistance of a Composite Coating Made by a Vacuum Fusion Sintering Method

Thermal fatigue behavior of a Ni-base alloy chromium carbide composite coating made by a vacuum fusion sintering method are dicussed,Results show that thermal fatigue behavior is associated with cyclic upper temperature and coating thickness,As the thickness of the coating decreases ,the ther-mal fatigue resistance increases,The thermal fatigue resistance cuts down with the thermal cyclic upper temperature rising,The crack growth rate decreases with the increase in cyclic number until crack arrests.Thermal fatigue failure was not found along the interface of the coating/matrix.The tract of thermal fatigue crack cracks along the interfaces of phases.     

中锰铁基合金激光熔覆层组织和接触疲劳性能

为了探讨齿类零件表面接触疲劳损伤后的修复技术,在45钢表面激光熔覆了一层中锰铁基合金。分别采用扫描电镜(SEM)、光学显微镜(OM)、X射线衍射仪(XRD)、HVS-1000型显微硬度计和JPM-1型接触疲劳试验机分析了中锰铁基合金熔覆层的显微组织,测试了其显微硬度和接触疲劳性能。结果表明:中锰铁基合金熔覆层与基体间形成了冶金结合,且其熔覆层无裂纹、气孔等缺陷;中锰铁基合金熔覆层的显微硬度为500~600HV,比渗碳层具有较高的抗接触疲劳性能,能够满足齿类零件的性能要求。     

n-SiO2/Ni复合镀层组织与接触疲劳性能

采用电刷镀技术制备了含n-SiO2/Ni复合镀层,测试了镀层的抗接触疲劳性能,探讨了在镀液中加入纳米铜颗粒对镀层抗接触疲劳性能的影响.结果表明,n-SiO2/Ni复合镀层接触疲劳寿命可达到一百万次以上;在镀液中加入纳米铜后,镀层接触疲劳寿命大幅度降低.加入纳米铜后镀层结构呈连续的层状,疲劳裂纹在层间萌生并沿层间扩展,导致在较短循环周次内发生失效.     

微缺陷对热喷涂涂层接触疲劳性能的影响

采用超音速等离子喷涂设备在45号钢基体上制备了三种含有不同微缺陷的NiCrBSi合金涂层。使用球盘式接触疲劳实验机对涂层的接触疲劳性能进行了测试,建立了Weibull失效概率图;使用扫描电子显微镜对涂层的微观结构和失效形貌进行了表征;比较了三种涂层的接触疲劳寿命及涂层的主要疲劳失效模式。结果表明,涂层内的微缺陷主要由微孔隙和微裂纹构成,涂层接触疲劳寿命的长短与这些微缺陷含量的多少成反比,涂层的孔隙率为2.5%,1.3%和2.1%,对应的接触疲劳寿命分别为7.77×105,8.99×105,7.81×105周次。同时,涂层微缺陷含量较少时涂层的失效模式主要以剥落失效为主;涂层微缺陷含量较多、结合强度较差时主要以分层失效为主;涂层内存在较大的孔隙可致使涂层的提早失效,同时涂层表面磨损失效的概率增加。     

Effect of thick DLC coating on fatigue behaviour of magnesium alloy in laboratory air and demineralised water

Rotating bending fatigue tests have been performed using Diamond‐like carbon (DLC) coated specimens of a wrought magnesium alloy, AZ80A, in laboratory air and demineralised water and the effect of DLC coating on fatigue and corrosion fatigue behaviour was studied. Three film thicknesses of 3.5 μm, 13 μm, and 25 μm (two‐layer film) were evaluated and particular attention was paid to the role of thick DLC coating. In laboratory air, the fatigue strengths of the DLC‐coated specimens were higher than that of the substrate specimen and increased with increasing film thickness. This was because hard DLC coating with good adhesion suppressed the crack initiation due to cracking of inclusions or cyclic slip deformation on the substrate surface. In demineralised water, the fatigue strength of the 3.5‐μm DLC‐coated specimen was the same as that of the substrate specimen due to the penetration of the water through pre‐existing film defects, while the 13‐μm and 25‐μm DLC‐coated specimens showed increased corrosion fatigue strength with increasing film thickness and also exhibited nearly the same fatigue strength as in laboratory air except for a few premature failed specimens, indicating a potential of thick DLC coating or two‐layer coating for complete improvement of corrosion fatigue strength in aqueous environments.     

Variables affecting the fatigue resistance of PVD-coated components

The effect of intrinsic properties of CrN coatings on fatigue behaviour was studied in this paper. The coating layer microhardness and the residual stresses characterising the surface film were measured and the obtained results were introduced in a numerical modelling predicting fatigue life procedure of coated components. The effect of a CrN monolayer film deposited on bulk samples, produced in 2205 duplex stainless steel, H11 tool steel or 6082 aluminium alloy was investigated. The fatigue limit of coated and uncoated samples was experimentally determined while the development of FEM models, confirmed by means of experimental tests, represents a powerful tool to predict fatigue life of coated components. The effects on the fatigue strength of coating and bulk material defects like droplets and non-metallic inclusions were considered along with the residual stress gradient characterising the coating and evaluated by means of X-ray measurements. The influence of the substrate material plastic deformation on the integrity of the coating was evaluated too.     

Fatigue Properties of Steel Coated with TiN by a PVD Process

Specimens of the steels S 6-5-2 (AISIM2) and 100 Cr 6 (AISI 52100) were coated with TiN by a reactive DC-magnetron-sputtering process. The fatigue behaviour of coated and uncoated specimens was investigated under cyclic bending. The fatigue limit of the uncoated steel S 6-5-2 is mainly governed by internal defects like carbide clusters and micropipes. Therefore, a coating has no influence on the fatigue limit. At high stress amplitudes the failure of the uncoated material is initiated at the specimen surface. Thus, coating of the surface causes higher mean lifetimes. The fatigue behaviour of the uncoated steel 100 Cr 6 is mainly governed by crack initiation at the surface of the specimens. At low stress amplitudes, a coating may shift the crack initiation place to the interior of the specimens. Hence, a slight improvement of the fatigue limit by coating is observed. At high stress amplitudes the coating has no influence on crack initiation and no improvement of the lifetime can be achieved by coating.     

Effect of high-temperature protective coatings on fatigue lives of nickel-based superalloys

This study concerns MCrAlY coatings (M is Ni, Co or both) sprayed by a vacuum plasma spraying process for protection against high-temperature corrosion and oxidation of gas turbine components, such as turbine blades and duct segments. The effect of high-temperature protective coatings on fatigue lives of nickel-based superalloys were investigated at high temperature under push–pull loading and rotary bending and then compared with uncoated superalloys, such as equiaxed IN738LC, unidirectional solidified CM247LC and single-crystal CMSX-2. The high-cycle fatigue lives of MCrAlY-coated superalloys at high temperature under push–pull loading showed an inferior performance when compared with the uncoated superalloys. This was because the crack initiation site was different. The high-cycle fatigue cracks of nickel-based superalloys initiated at casting cavities which were exposed on the specimen surface, whereas the high-cycle fatigue cracks of MCrAlY-coated specimens initiated at interface defects, such as small pores and grid residue, between the MCrAlY coating and the substrate and grew into the MCrAlY coating, and then into the substrate. Similarly, the rotary bending fatigue properties of MCrAlY-coated superalloys at high temperature showed an inferior performance when compared with the uncoated superalloys. This is because of a high stress due to the higher Young's modulus of the MCrAlY coating (in comparison with the substrate) being induced at the MCrAlY coating surface. The crack initiation site was on the specimen surface in both cases of the nickel-based superalloys and the MCrAlY-coated superalloys, respectively. As a result, it was considered that, for rotary bending tests, the fatigue life reduction was due to the high stress that originated from the difference of elastic constants between the MCrAlY coating and the superalloy. Consequently, in fatigue life design it is necessary to take account of the stress levels in a coating layer.