化学镀镍–磷–二硫化钼复合镀层及其磨损行为的研究

在45钢基体上化学镀制备得到Ni–P–Mo S2复合镀层,研究了镀液Mo S2添加量(镀层Mo S2含量)对镀层磨损行为的影响。采用X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)等手段表征了镀层的形貌、微观结构和磨损特征,探讨了不同镀层的磨损机制。400°C热处理使镀层金属由非晶态转变为晶态,显微硬度提高,但Mo S2的物相不变。Ni–P镀层的显微硬度(热处理后为1 040 HV)较高,在摩擦过程中能形成对磨损面起保护作用的摩擦层,故Ni–P镀层具有良好的耐磨性,其磨损机制为粘着磨损和转移。镀液添加1 g/L Mo S2时,所得Ni–P–Mo S2复合镀层具有更优异的耐磨性,这是其高显微硬度(热处理后为735 HV)和Mo S2润滑效应的共同作用,以轻微磨粒磨损和转移为主要磨损机制;镀液添加过量(2 g/L)Mo S2时,复合镀层的显微硬度(热处理后为533 HV)较低,摩擦过程中表面不能形成摩擦层,其耐磨性极差,磨损机制为严重的粘着磨损和磨粒磨损。     

可溶性阳极电刷镀纳晶Ni-P-SiC复合镀层的耐磨损性能

采用可溶性镍阳极电刷镀方法,在铜片上制备了Ni-P纳晶镀层和Ni-P-SiC复合镀层,镀层表面平整、致密、无裂纹.纳米颗粒的加入没有改变镀层的纳米晶结构,对镀层磷含量影响不大.硬度测试和摩擦磨损试验表明:纳米SiC的加入起到细晶强化和弥散强化作用,可以提高镀层的硬度和耐磨性能:添加纳米颗粒后镀层磨损方式由黏着磨损转变为磨粒磨损.     

镁合金化学复合镀Ni-P/纳米SiC工艺的研究

在AZ 91D镁合金表面制备Ni-P/纳米SiC化学复合镀层.探讨镀液中纳米SiC微粒的质量浓度对镀速、复合镀层性能等的影响.利用扫描电镜观察镀层表面形貌,采用能谱分析仪进行镀层表面成分的定性分析,采用显微硬度计测试镀层硬度,并对不同工艺下获得的镀层进行快速磨损实验.结果表明:镀液中添加适量的纳米SiC微粒,镀速和镀层硬度都有显著的提高.当镀液中纳米SiC的质量浓度为9 g/L时,镀速可达到25.6 μm/h;当镀液中纳米SiC的质量浓度为7 g/L时,镀层的维氏硬度可达到9 380 MPa;同时镀层的耐磨性能相比于Ni-P合金镀层的也有显著提高.     

Ni—P—W—SiC复合镀层的研制

前言晶化处理因提高 Ni—P 耐蚀镀层的显微硬度值。可明显改善镀层的耐磨性;外加硬质相又进一步提高了这类复合镀层的耐磨性.400℃真空处理后,这类复合化学镀层的耐磨试验结果表明(图一)。SiC 硬质颗粒对改善复合镀层耐磨性的效果最佳.复合镀层具有优良的使用性能和较明显的经济效益,是当前涂层技术发展的一个重要前沿.本文叙述了 Ni—P—W—SiC 复合电镀层的研制、质量和部分性能测试结果.     

电流密度对碳化硅电镀镍的影响

以SiC片为基体,分别在直流(DC)电源和脉冲(PC)电源下电镀Ni。研究了电流密度对Ni镀层表面形貌、粗糙度、显微硬度以及SiC和Ni镀层刻蚀选择性的影响。结果表明,随直流电流密度增大,Ni镀层的表面形貌先变好后变差,表面粗糙度先减小后增大,显微硬度和SiC/Ni刻蚀选择比逐渐减小。随脉冲电流密度增大,Ni镀层的表面形貌和粗糙度的变化趋势与直流电镀时相近,但显微硬度和SiC/Ni刻蚀选择比均逐渐增大。当电流密度较大时,在相同电流密度下脉冲电镀Ni层的各项性能均优于直流电镀Ni层。在1.4 A/dm²的平均电流密度下脉冲电镀可获得综合性能较优的Ni镀层。     

含纳米粉镀液的电刷镀复合镀层试验研究

应用电刷镀技术制备了含有纳米SiC粉的镍基复合镀层，对该复合镀层的显微硬度和摩擦学性能进行了测试，并讨论了主要工艺参数对这些性能的影响规律。测试结果表明：纳米SiC粉的加入可以一定程度的提高复合镀层的硬度。快镍复合纳米SiC镀层的摩擦因数低于快镍镀层的摩擦因数。镀液中纳米SiC粉和添加剂浓度增加时，复合镀层的摩擦因数有降低趋势。与快镍镀层相比，快镍复合纳米SiC镀层的耐磨性有较大幅度的提高。还采用光学显微分析(OM)和电子探针(EPMA)研究了对该复合镀层的表面形貌、组织和元素分布特点，并提出了纳米SiC粉与镍共沉积的机理。     

SiC纳米颗粒增强型复合镀层的研究进展

SiC纳米颗粒作为增强相添加到复合镀层中,可提高镀层的综合性能。分析了SiC纳米颗粒对镀层的表面形貌、显微硬度、耐磨性和耐腐蚀性等性能的影响机理,讨论了SiC纳米颗粒浓度、电流密度和搅拌速度等工艺参数对制备复合镀层的影响,阐述了不同电沉积方式对制备复合镀层的影响,指出在SiC纳米颗粒增强型复合镀层研究中尚需解决的若干问题。     

活塞环材料的化学复合镀层与性能

本文研究了铸铁活塞环材料表面化学镀复合有SiC的Ni—P合金镀层。研究结果表明，Ni—P合金加热处理后，其Ni—P过饱和固溶体产生脱溶沉淀，析出第二相Ni3P，产生沉淀强化，SiC柱子复合后，产生分散强化，镀层硬度进一步提高，从而提高了耐磨性能。与镀铬、磷化处理相比，Ni-P合金层摩擦系数低，SiC镀层磨损体积低，抗磨能力强，耐磨性优良。     

Ni—Fe／Ni—P—W双层合金镀层的制备及性能

采用电沉积法,在45#钢上制备了Ni-Fe/Ni-P-W双层合金镀层.采用原子吸收分光光度法和X射线衍射分别测定了镀层的化学成分及相结构,并测试了其显微硬度和耐腐蚀性能.结果表明,该双层合金镀层具有较强的显微硬度,在5%(质量分数)NaCl溶液中具有比Ni-P-W合金镀层更优异的耐蚀性能.因此,该双层合金镀层可用作防腐耐磨镀层.     

脉冲电沉积Ni-SiC纳米复合镀层的工艺及性能

采用脉冲电沉积技术在铜基表面制备Ni-SiC纳米复合镀层。利用扫描电镜(SEM)、透射电镜(TEM)、显微硬度计及电化学测试,研究了纳米SiC微粒的质量浓度对复合镀层的表面形貌、组织结构、显微硬度以及耐蚀性的影响。结果表明:当纳米SiC微粒的质量浓度为6～9g/L时,制备的复合镀层组织细密,显微硬度最高可达7 730MPa,并且耐蚀性也有了较大的提高。     

Wear behavior of SiC nanowire-reinforced SiC coating for C/C composites at elevated temperatures

To improve the wear resistance of SiC coating on carbon/carbon (C/C) composites, SiC nanowires (SiCNWs) were introduced into the SiC wear resistant coating. The dense SiC nanowire-reinforced SiC coating (SiCNW-SiC coating) was prepared on C/C composites using a two-step method consisting of chemical vapor deposition and pack cementation. The incorporation of SiCNWs improved the fracture toughness of SiC coating, which is an advantage in wear resistance. Wear behavior of the as-prepared coatings was investigated at elevated temperatures. The results show that the wear resistance of SiCNW-SiC coating was improved significantly by introducing SiC nanowires. It is worth noting that the wear rate of SiCNW-SiC coating was an order of magnitude lower than that of the SiC coating without SiCNWs at 800 °C. The wear mechanisms of SiCNW-SiC coating at 800 °C were abrasive wear and delamination. Pullout and breakage of SiC grains resulted in failure of SiC coating without SiCNWs at 800 °C.     

Tribological performance of SiC coating for carbon/carbon composites at elevated temperatures

SiC coating was deposited on carbon/carbon (C/C) composites by chemical vapor deposition (CVD). The effects of elevated temperatures on tribological performance of SiC coating were investigated. The related microstructure and wear mechanism were analyzed. The results show that the as-deposited SiC coating consists of uniformity of β-SiC phase. The mild abrasive and slight adhesive wear were the main wear mechanisms at room temperature, and the SiC coating presented the maximum friction coefficient and the minimum wear rate. Slight oxidation of debris was occurred when the temperature rose to 300?°C. As the temperature was above 600?°C, dense oxide film formed on the worn surface. The silica tribo-film replaced the mechanical fracture and dominated the frication process. However, the aggravation of oxidation at elevated temperatures was responsible for the decrease of friction coefficient and the deterioration of wear rate. The SiC coating presented the minimum friction coefficient and the maximum wear rate when the temperature was 800?°C.     

粘结剂对超音速火焰喷涂碳化钨涂层磨粒磨损性能的影响

采用超音速火焰喷涂(HVOF)工艺在35钢基体上制备了WC-10Ni涂层和WC-12Co涂层,研究了镍、钴这两种粘结剂对WC涂层的显微硬度、摩擦系数和抗磨粒磨损性能的影响,采用扫描电子显微镜观察涂层磨损前后的表面形貌,探讨了WC涂层的磨粒磨损机理。结果表明,以HVOF方法制备的2种WC涂层均有较高的显微硬度,WC-10Ni涂层和WC-12Co涂层与SiC砂纸摩擦副之间的干摩擦系数相差不大。2种涂层在低载荷下均有较好的抗磨粒磨损性能,但在较高载荷下WC-12Co涂层的抗磨性明显优于WC-10Ni涂层。2种涂层的磨粒磨损形式主要为均匀磨耗磨损,磨损机理以微切削和微剥落为主。WC-12Co涂层的磨损表面损伤较轻微,综合性能优于WC-10Ni涂层。     

The effects of adding nano-alumina filler on the properties of polymer-derived SiC coating

In this paper, SiC coating was prepared using the polymer-derived ceramic method; then the effect of nano-alumina as a filler material was studied. First of all, polycarbosilane(PCS) was dissolved in xylene; after that, different amounts of nano-alumina particles were added to the solution. The coating was deposited on the alumina substrate using the dip-coating method; this was followed by sintering at 1200℃. The phase content and microstructure of the samples were studied by X-ray diffraction and scanning electron microscope methods, respectively. Nanohardness, Young's modulus, and coating adhesion were investigated by a nanoindentation method. The sheet resistance was evaluated using the four-point probe technique; also, the wear resistance of the coating was studied by applying the pin-on-disk method. It was found that the addition of the nano-alumina filler up to 20 wt% drastically improved the adhesion and wear resistance of the SiC coating.     

工程车活塞杆用45~#钢电沉积Ni-WC纳米复合镀层的研究

在工程车活塞杆常用材料45#钢表面电沉积Ni-WC纳米复合镀层。分析了纳米复合镀层的表面形貌和物相结构,测试了纳米复合镀层的耐磨性和耐蚀性,并与45#钢的性能做比较。结果表明:纳米复合镀层表面较平整、均匀,结构较致密,主要由Ni相、WC相组成,Ni相的质量分数为81.25%,WC相的质量分数为6.53%,孔隙率低于0.5%,平均摩擦因数约为0.28;相同条件下,纳米复合镀层的腐蚀速率低于45~#钢的;纳米复合镀层能够提供有效的磨损防护和腐蚀防护,提高45~#钢的耐磨性和耐蚀性。     

化学镀制备高耐蚀耐磨Ni-P-SiC复合镀层

研究了Ni-P-SiC复合镀层的制备工艺和性能以及SiC含量对镀层性能的影响。采用Taber试验机对Ni-P-SiC复合镀层的磨损性能进行了测试,并用VHX-100型三维视频显微镜对磨损形貌进行了观察,分析了复合镀层的磨损机理。结果表明:SiC颗粒的加入能有效地降低摩擦副之间的犁沟效应及摩擦表面发生粘着的面积,从而减少镀层的磨损。采用电化学实验等手段研究了Ni-P-SiC复合镀层的耐蚀性能。当复合镀层均匀一致,能起到一个良好的屏蔽作用时,耐蚀性十分优异;而镀层缺陷的存在将导致耐蚀性能降低。     

Molten salt synthesis and antioxidation property of SiC-coated mesocarbon microbeads

Mesocarbon microbead (MCMB) is a prospective candidate as the raw material for nuclear graphite. However, the poor resistance to high-temperature oxidation limits its application. Herein, a dense SiC coating was prepared by molten salt synthesis on the surface of MCMB to improve its antioxidation performance. The effect of molten salt synthesis reaction time on the phase composition, microstructure, and antioxidation performance of the SiC-coated MCMB particles was investigated. A theoretical model was established to explain the SiC coating growth rule well, in conformity with the carbon vacancy diffusion mechanism in SiC coating. The SiC coating synthesized for 7 h with the thickness of .385 µm remarkably promoted the high-temperature antioxidation property of MCMB. The kinetics analysis indicated that the SiC coating obstructed the oxygen diffusion effectively during the oxidation process. The as-fabricated SiC-coated MCMBs with good oxidation resistance show great promise for application in nuclear industry and other antioxidative fields.     

机械飞轮基体电泳沉积SiC涂层的研究

使用电泳技术在机械飞轮用30CrMo钢表面制备了SiC涂层,并研究了SiC的质量浓度对SiC涂层的厚度、表面形貌、硬度及耐蚀性的影响。结果表明:增加SiC的质量浓度有利于提高SiC涂层的厚度、硬度及耐蚀性。当SiC的质量浓度为35 g/L时,团聚作用和界面效应使得SiC涂层的厚度明显减小,表面裂纹增多,导致SiC涂层的硬度及耐蚀性大大降低。在SiC的质量浓度为30 g/L的条件下电泳沉积的SiC涂层具有最佳的硬度和耐蚀性。     

包埋法制备碳/碳复合材料碳化硅涂层缺陷的形成机制及控制

用包埋法在碳/碳(C/C)复合材料表面制备了碳化硅(SiC)涂层及改性涂层.用扫描电镜观察涂层的微观形貌.从理论上探讨了涂层缺陷的形成机制,分析了改性剂对SiC涂层形貌、晶粒尺寸的影响.结果表明:添加改性剂后,涂层晶粒变小,涂层致密,表面未出现裂纹,断面孔洞的数量减少,尺寸减小.在1 773K的抗氧化性比未添加改性剂涂层的显著提高.     

Oxidation resistance of SiC nanowires reinforced SiC coating prepared by a CVD process on SiC‐coated C/C composites

Oxidation protective SiC nanowires‐reinforced SiC (SiCNWs‐SiC) coating was prepared on pack cementation (PC) SiC‐coated carbon/carbon (C/C) composites by a simple chemical vapor deposition (CVD) process. This double‐layer SiCNWs‐SiC/PC SiC‐coating system on C/C composites not only has the advantages of SiC buffer layer but also has the toughening effects of SiCNWs. The microstructure and phase composition of the nanowires and the coatings were examined by SEM, TEM, and XRD. The single‐crystalline β‐SiC nanowires with twins and stacking faults were deposited uniformly and oriented randomly with diameter of 50‐200 nm and length ranging from several to tens micrometers. The dense SiCNWs‐SiC coating with some closed pores was obtained by SiC nanocrystals stacked tightly with each other on the surface of SiCNWs. After introducing SiCNWs in the coating system, the oxidation resistance is effectively improved. The oxidation test results showed that the weight loss of the SiCNWs‐SiC/PC SiC‐coated samples was 4.91% and 1.61% after oxidation at 1073 K for 8 hours and at 1473 K for 276 hours, respectively. No matter oxidation at which temperature, the SiCNWs‐SiC/PC SiC‐coating system has better anti‐oxidation property than the single‐layer PC SiC coating or the double‐layer CVD SiC/PC SiC coating without SiCNWs.