1100℃下MoSi_2涂层的高温摩擦磨损性能研究

为提高K403镍基高温合金的高温耐磨损能力,采用大气等离子喷涂在镍基上制备了金属间化合物MoSi2涂层,比较分析了基体和涂层与Al2O3配对摩擦副在1100℃下的高温摩擦磨损性能,并采用X射线衍射仪和扫描电镜对摩擦磨损表面进行了物相、形貌和成分分析,进而分析了基体和涂层的磨损机理。研究结果表明:K403合金的摩擦因数在0.35～0.5范围内变化,而MoSi2涂层的摩擦因数在0.65左右波动;MoSi2涂层的磨损率约是基体材料的0.5倍,涂覆MoSi2涂层后,提高了镍基高温合金耐高温磨损能力;镍基合金的高温摩擦磨损机制主要为氧化磨损和疲劳断裂,载荷较小(10N)时,MoSi2涂层的磨损机制主要表现为氧化磨损,较大载荷(40N)时,MoSi2涂层的磨损机制主要表现为氧化磨损和疲劳脆性断裂。     

不同工艺制备镍基合金涂层的耐高温磨损性能

以商用Ni60合金粉为涂层材料,采用火焰重熔、等离子堆焊、中频感应重熔等3种工艺在45钢基体上制备镍基合金涂层,研究了其物相组成、显微组织、显微硬度和耐高温磨损性能。结果表明:制备的镍基合金涂层的孔隙率均较低;火焰重熔和中频感应重熔涂层中的硬质相主要为均匀分布的碳化物,但中频感应重熔涂层的晶粒较小,显微硬度较高;等离子堆焊涂层的晶粒粗大,硬质相以粗大的硼化物为主,且偏聚严重,显微硬度最低;中频感应重熔涂层的耐高温磨损性能最好,其磨损形式为黏着磨损和磨粒磨损,火焰重熔涂层的耐高温磨损性能稍差,其磨损形式主要为黏着磨损,等离子堆焊涂层的耐高温磨损性能最差,其磨损形式为黏着磨损和疲劳磨损。     

不同铁含量镍-铁合金镀层的摩擦磨损性能

采用电沉积方法在LY12CZ铝合金表面制备了不同铁含量的镍-铁合金镀层,研究了铁含量对合金镀层硬度和摩擦磨损性能的影响;并根据镀层的磨损形貌探讨了其磨损机理。结果表明:当铁含量低于12.63%(原子分数,下同)时,随着铁含量增加,镀层的硬度增加,摩擦因数减小,耐磨性能提高;当铁含量为由12.63%增至23.59%时,镀层的摩擦因数略有增加,硬度和耐磨性能有所降低;镍镀层的主要磨损机理为显微推碾,随着铁含量的增加,镍-铁合金镀层的磨损机理由显微推碾转变为显微切削。     

Al2O3-20%TiO2涂层与Al2O3-40%TiO2涂层磨损性能的对比研究

主要对比分析了Al2O3-20%TiO2涂层和Al2O3-40%TiO2涂层与浸树脂石墨进行干滑动摩擦时的磨损性能.实验表明:Al2O3-20%TiO2涂层与Al2O3-40%TiO2涂层的磨损率都随摩擦时间的增大呈先降低后增大的趋势;在相同实验条件下,Al2O3-20%TiO2涂层的耐磨性能要优于Al2O3-40%TiO2涂层材料,且摩擦过程中的主要磨损机理为:粘着磨损和脆性断裂.     

钽对激光熔覆镍基涂层的裂纹敏感性及力学性能的影响

研究钽(Ta)元素对激光熔覆Ni60镍基涂层的显微组织、裂纹敏感性、硬度和耐磨粒磨损性能的影响。扫描电镜结果显示镍基涂层的裂纹多为沿粗大硬质相晶界开裂,具有典型的热裂纹特征。镍基涂层中加入Ta后,TaC颗粒首先在熔池中形核长大,抑制了M7C3碳化物长大。随着Ta质量分数的增加,涂层表面裂纹的数量和长度明显减少,这得益于初生M7C3碳化物颗粒的细化以及涂层韧性的增加。加入Ta后,尽管涂层硬度有所下降,但是磨粒磨损试验结果显示涂层耐磨粒磨损性能比纯Ni60镍基粉末大幅提高,原因如下:Ta通过固溶强化γ-Ni基体相提高其支撑硬质相的能力;Ta减小M7C3碳化物的高宽比,降低碳化物的脆裂性;此外,原位生成的细小TaC颗粒在摩擦过程中不易脱落,更好地抵御磨粒对材料的切削。     

等离子弧功率对Al2O3-13wt％TiO2涂层组织与磨损性能的影响

采用大气等离子喷涂方法在Q235钢基体上制备了不同等离子弧功率的Al2O3-13wt％TiO2涂层,粒度为(20～40)μm.采用扫描电镜、X射线衍射仪和能谱仪等对涂层微观形貌、相组织结构进行表征,测定了涂层截面孔隙率、沉积厚度、显微硬度以及干摩擦磨损性能.等离子弧功率为29640W时涂层质量较好,截面显微硬度达1145 HV0.2、沉积厚度为338μm,孔隙率为3.9％,干摩擦磨性能最佳.在较大载荷下犁沟效应明显,涂层失效形式表现为颗粒剥落、磨粒磨损.载荷减小时,涂层微观脆性断裂显著,磨损失效形式为疲劳剥落和显微犁削.     

Cu添加对等离子喷涂Al_2O_3涂层和AT13涂层性能的影响

在20钢表面运用等离子喷涂技术分别制备了Cu-Al_2O_3涂层和Cu-AT13涂层,并测试了涂层显微硬度、结合强度以及摩擦学性能。结果表明,Cu-Al_2O_3涂层较Cu-AT13涂层,平均显微硬度提高,结合强度减小,摩擦系数降低,磨损率降低,两种复合涂层的主要磨损机制均为剥落。     

模具钢表面Co/TiC熔覆层的组织与高温磨损性能

利用6 kW横流CO2激光器制备了Co50熔覆层和不同成分配比的Co/TiC复合涂层来改善H13模具钢表面的热磨损性能.借助X射线衍射(XRD)、扫描电子显微镜(SEM)、显微硬度计和高温摩擦磨损试验机分析了涂层的结合特征、物相组成和不同温度下的摩擦磨损性能.结果表明,当预置层粉末TiC含量(重量百分比)小于等于20％时,熔覆层与H13钢基材呈良好的冶金结合;随着TiC含量的增加,Co/TiC复合涂层截面平均显微硬度呈上升趋势,但涂层中基体相种类减少:Co+10％TiC涂层由TiCo3、Cr2Ni3和Cr-Ni-Fe-C组成,Co+20％TiC涂层由Cr2Ni3和γ-Co组成,Co+30％TiC涂层为γ-Co固溶体.Co+ 20％ TiC涂层的高温耐磨性比C050涂层显著提高,摩擦系数平稳;700℃时复合涂层的磨损机制主要为氧化磨损和疲劳磨损.结果显示Co+20％TiC涂层具有良好的综合性能.     

超声辅助激光熔覆TiCN镍基涂层组织及性能研究

为了探究超声频率对激光熔覆涂层的影响，设置5组对照实验。通过施加超声频率0 kHz、26 kHz、30 kHz、34 kHz和38 kHz辅助制备出TiCN增强镍基涂层，对各涂层宏观形貌、显微组织及耐磨性进行了研究。结果显示：施加超声不会使涂层产生新的物相且在一定程度上促进TiCN增强相的生成；增加超声频率，涂层中气泡数量减少，晶粒更细小紧密，涂层中团聚现象减少；增加超声频率，涂层显微硬度增加，当超声频率为38 kHz时涂层显微硬度最高且变化平稳；对比未施加超声的涂层，施加超声频率38 kHz时的涂层磨损量减少约30%，且主要磨损由粘着磨损转变为轻微犁削。     

油润滑下MoSi2材料的摩擦磨损性能

运用M-200型摩擦磨损试验机测定了油润滑条件下MoSi2与45调质钢、45淬火钢和CrWMn钢配对时的摩擦磨损性能，采用扫描电镜和微探针分析了摩擦副表面的形貌，探讨了磨损机理：结果表明：采用20号机械油润滑可有效地降低MoSi2材料的磨损率及摩擦因数；与低硬度的45调质钢和45淬火钢对摩时，MoSi2材料的主要磨损机制为晶间断裂、疲劳断裂、轻微粘着磨损和磨粒磨损；MoSi2材料与高硬度的CrWMn钢对摩时，主要磨损机制表现为粘着磨损、微犁削式磨粒磨损，并在偶件表面材料凸点的前端形成楔块。     

Tribological Behaviour of Nanostructured Al2O3-3 wt% TiO2 Coating Against Steel in Dry Sliding

Nanostructured and conventional Al₂O₃-3 wt% TiO₂ coatings were deposited by atmospheric plasma spraying. The wear and friction properties of both coatings against a steel ball under dry friction conditions were examined. It was found that the wear resistance of the nanostructured Al₂O₃-3 wt% TiO₂ coating was superior to that of the corresponding conventional counterpart. The improvement in wear resistance of the nanostructured coating was attributed to its higher toughness and cohesion strength between splats. As for the nanostructured coating, the wear mechanism was mainly adhesion with micro-abrasion at low loads (20 N). At high loads (80 N), the wear of the nanostructured coating was controlled by plastic deformation and associated delamination along the splat boundaries, which was similar to that of the conventional coating at low loads. However, the failure of the conventional coating was predominantly brittle fracture within the splats and delamination between splats at high loads.     

稀土强韧化MoSi2材料的摩擦学性能

采用高温自蔓延和真空烧结合成了含0.8%（质量分数）稀土/MoSi2复合材料。在MRH-5A型环-块摩擦磨损试验机上,考察了其与调质45#钢配对时的摩擦磨损特性。运用带有微探针的KYKY2800型扫描电镜分析了其磨损表面形貌,探讨了该材料的磨损机制。结果表明：在干摩擦同等条件下,稀土/MoSi2复合材料比纯MoSi2材料具有更好的抗磨损性能,其磨损率比纯MoSi2至少降低了68%。低速（200r/min）时,RE/MoSi2复合材料的磨损机制主要是粘着磨损,随着载荷的增加,粘着磨损脱落更为严重;在高速（400r/min）和低载荷（78N）下,RE/MoSi2复合材料的磨损机制仍以粘着磨损为主,在重载荷（274N）下,RE/MoSi2复合材料的磨损机制主要为粘着磨损和疲劳脆性断裂。     

Y2O3改性石墨/CaF2/TiC/镍基合金复合涂层微观组织与摩擦学性能研究

为提高石墨/CaF₂/TiC/镍基合金（GCTN）复合涂层的力学性能和摩擦学性能,运用等离子喷涂技术在45钢表面制备了Y₂O₃改性GCTN复合涂层,研究了Y₂O₃对复合涂层的微观组织、显微硬度、断裂韧性和摩擦磨损性能的影响。结果表明：Y₂O₃改性GCTN复合涂层主要由γ-Ni、CrB、Cr7C₃、TiC、CaF₂和石墨等物相组成。Y₂O₃在等离子火焰加热作用下与C元素反应生成活性元素Y,Y净化了复合涂层的微观组织,并细化了CrB、Cr₃C7等硬质相晶粒,提高了其致密性。当Y₂O₃质量分数为0.5%时,复合涂层的显微硬度和断裂韧性分别为593.3MPa和6.82MPa·m^1/2,比不含Y₂O₃的复合涂层分别增大了8%和22%,其机理主要是Y₂O₃细化了CrB、Cr₃C₇等硬质相晶粒,起到了细化强化作用。由于GCTN-0.5Y₂O₃复合涂层的显微硬度和断裂韧性显著提高,减少了其黏着磨损和微观断裂磨损,因而GCTN-0.5Y₂O₃复合涂层的摩擦因数和磨损率最小,分别为0.085和0.39×10-3mm3/m。     

AlNiZr非晶纳米晶复合涂层的腐蚀磨损行为研究

为提高海洋极端环境下钢结构材料的耐腐蚀磨损性能,采用高速电弧喷涂技术制备了一种AlNiZr非晶纳米晶复合涂层,并研究了该涂层在质量分数为3.5%的NaCl溶液中的腐蚀磨损行为。结果发现,AlNiZr涂层组织较为均匀,致密性较好,相结构由非晶、纳米晶及晶化相共同组成,涂层非晶体积分数约为64.93%,平均显微硬度值为363HV0.1,与45钢基体之间的平均结合强度约为30.8 MPa;在干摩擦条件下其平均摩擦因数约为0.125,磨损体积约为0.134 mm3,磨痕宽度约为882.4 μm,磨损失效机制以氧化磨损和脆性剥层磨损为主,并伴有轻微磨粒磨损;在腐蚀介质条件下,由于受到腐蚀介质的润滑减摩作用,导致涂层的平均摩擦因数、磨损体积、磨痕宽度均有明显减小,其平均摩擦因数约为0.058,磨损体积约为0.02216 mm3,磨痕宽度约为314 μm,腐蚀磨损失效机制主要表现为剥层磨损形式,同时磨损起主导作用、腐蚀次之。与纯铝涂层相比,AlNiZr涂层表现出优异的耐腐蚀磨损性能。     

Dry sliding friction and wear properties of metallic glass coating and martensite stainless coating

The wire arc spraying process was used to prepare FeB-based metallic glass coating and 3Cr13 coating. The effects of wear parameters, such as sliding distance, linear speed and normal loads, on the wear performances of the coatings were analyzed in detail. The results showed that, with increase in sliding distance, linear speed and normal loads, the volume losses of the metallic glass coatings increased. The relationships between wear behavior and microstructure of the coatings were discussed. The metallic glass coating had excellent wear resistance. The relatively wear resistance of the metallic glass coating was about 2.6 times that of the 3Cr13 coating under the same testing conditions. The main failure mechanism of the metallic glass coating was brittle failure and fracture.     

镁合金表面再制造AlCoTi非晶涂层组织及力学性能研究

采用高速电弧喷涂技术在AZ91镁合金表面制备了高非晶含量AlCoTi涂层,研究了涂层显微组织、力学性能、摩擦磨损及电化学腐蚀性能。结果表明,涂层呈典型的层状结构,其结构紧凑,与镁合金基体结合良好,孔隙率约为1.63%。涂层的组织主要由非晶相、纳米结构的α-Al和Al3Ti相组成。相比于AZ91镁合金,AlCoTi非晶涂层具有更高的显微硬度和耐磨性能：涂层的显微硬度约为511.3Hv0.1,远高于AZ91镁合金(62Hv0.1);在相同的磨损条件下,非晶涂层相对耐磨性约为晶体结构AZ91镁合金的3.9倍,其主要磨损机制为脆性剥落。在0.6 mol/L NaCl溶液中,非晶涂层自腐蚀电位、自腐蚀电流密度和电荷转移电阻分别为-0.696V、0.741 8μA/cm²和33 660?·cm²,明显优于AZ91镁合金的-1.392V、769.3μA/cm²和1 914?·cm²。通过对镁合金表面不同防护涂层的电化学腐蚀性能和显微硬度比较分析,本研究为镁合金提供一种低成本、高性能的涂层材料及再制造关键技术。     

Tribological properties of thin coatings based on epilams modified by nanosized silica

The results of studying the effect of the Tarkosil SiO₂ nanopowder on the tribological behavior of the steel-antifriction coating model systems are presented. The dependences of the coefficient of friction, the wear resistance, and the microhardness of the test specimens on the concentration of the silica nanopowder in the thin coatings are obtained. It is shown that the modification of the coatings by 1% of silica favors an increase in their microhardness and a decrease in their coefficient of friction. At the limiting concentrations of the nanosized filler and under heavy specific loads, the brittle fracture of the coatings occurs.     

Tribological behavior of plasma sprayed Cr2O3-3%TiO2 coatings

Tribological behaviors of plasma-sprayed conventional and nanostructured Cr₂O₃-3%TiO₂ ceramic coatings (i.e., CC3T and NC3T, respectively) using pin on disc type dry sliding and pot type slurry erosion test were investigated in the present work. The experimental results indicated that there were two main wear mechanisms, plastic smearing and adhesive tearing, in the worn coatings under dry sliding. Plastic smearing corresponded to a lower average friction coefficient and wear rate, while adhesive tearing corresponded to higher values. The erosive environment selected for the slurry erosion experiments include 10, 20 and 30% of SiO₂ slurry concentrations in water with particle size 75-106 μm. The main damage mechanism observed in all the coatings submitted to slurry erosion were the formation and propagation of brittle cracks resulting in the detachment of coating surface material. Microstructural investigation was also carried to investigate the wear and erosion mechanism of the coatings using FE-SEM and EDS analysis. Properties like microhardness and porosity were also investigated for these coatings. Tribological performance of NC3T was better as compared to CC3T as observed in the present work.     

Preparation of Nickel-Cobalt/Carborundum Carbide Composite Coatings by Supergravity Field-Enhanced Electrodeposition

Nickel-cobalt/silicon carbide(Ni-Co/SiC) composite coatings were fabricated by supergravity field-enhanced electrodeposition. The surface morphology and the distribution of the SiC particles in the coatings were examined by scanning electron microscope and energy dispersive X-ray spectrometry. The preferred orientations of the coatings were measured by X-ray di ractometry. The wear resistance and microhardness were measured by a reciprocating tribometer and a microhardness instrument, respectively. The results revealed that the use of the supergravity field enhanced the smoothness of the as-deposited Ni-Co/SiC coatings, and the SiC nanoparticles were uniformly distributed in comparison with that for conventional electrodeposition. When the rotation speed of the cathode, which provided the supergravity field, was 800 r/min, the SiC content in the coating reached a maximum of 8.1 wt%, which was a much higher content than the 2.2 wt% value obtained under conventional electrodeposition. The highest coating microhardness of 680 HV was also observed at this rotation speed. In addition, the wear resistance of the as-prepared Ni-Co/SiC coatings exhibited improved performance relative to that prepared under normal gravity. A minimum wear weight loss of 1.4 mg together with an average friction coe cient of 0.13 were also realized at a rotation speed of 800 r/min, values which were much lower than those for normal gravity.     

Coarse cemented WC particle ceramic-metal composite coatings produced by laser cladding

Coarse cemented WC particle (600–900 μm) ceramic-metal composite coatings with a thickness of 1.2–1.5 mm were cladded on 20Ni4Mo steel surfaces using a laser of power 2 kW, diameter 5 mm and traverse speed 4–20 mm s⁻¹. The weight fraction of WC particles was 67 wt%. Compared with the behaviour of cemented WC particles of the same size and ratio in atomic hydrogen welded coating (AHWCs), the WC particles in laser-cladded ceramic-metal coating (LCCCs) show a uniform distribution in the molten zone. The microhardness of WC particles in LCCCs is 13.7–16.2 GPa, and their sizes are almost unchanged, which indicates that little heat damage occurs during laser cladding. The abrasive wear results showed that LCCCs have superior wear resistance to AHWCs. The wear mechanisms for LCCCs and AHWCs are analysed and compared.