电镀Fe-Cr-Ni及Fe-Ni合金相组成研究

用x-射线衍射法测定了Fe-cr-Ni合金镀层及Fe-Ni合金镀层的相组成。这些合金镀层的相组成很复杂。一般含有Cr、Fe碳化物、富Cr、富Ni、富α-Fe及γ-NiFe相。在Fe-Cr-Ni合金镀层中,Fe含量80％左右时,合金含(Cr、Fe)_7C_3,相。当合金中Ni的含量增加时,富Ni相消失,而合金中Cr含量增加时有Fe-cr相形成。这种不形成均匀固溶体合金相的现象称为相分离。     

Al含量对热镀锌—铝合金镀层组织结构的影响

在改良森吉米尔法热镀锌机组上采用Al质量分数分别为8%、10%、12%和15%的镀浴，制备了Zn–Al合金镀层，利用扫描电镜(SEM)和能谱仪(EDS)分析了它们的微观组织结构。结果表明，Zn–Al合金镀层由先共晶富Al相和Zn–Al二元共晶组织组成，其中二元共晶组织由富Al相和富Zn相组成。随着镀浴中Al质量分数增大，Zn–Al合金镀层的先共晶富Al相的含量增大，枝晶变粗、变多，逐渐转变为网络结构；Zn–Al二元共晶组织的占比则减少，逐渐由网格状变为细条状。     

扩散退火温度对钢表面铁–铝金属化合物镀层的影响

通过热浸铝和扩散退火处理在45钢表面制备Fe–Al金属间化合物镀层。研究了镀层微观形貌、物相和显微硬度随退火温度升高的变化规律。结果表明,经700°C扩散退火处理的热浸镀铝钢,镀层与基体之间呈长舌状结合。800°C退火处理后,长舌状形貌基本消失,镀层厚度增至300μm。900~1 000°C退火处理后,镀层呈连续的双层结构,与钢基体结合得更紧密。随扩散退火温度升高,镀层由富铝相Fe2Al5转变为富铁相Fe Al和Fe3Al,导致镀层显微硬度降低。     

锌铝镁镀层于3.5%NaCl溶液中腐蚀行为的研究

使用扫描电镜及扫描探针分析了锌铝镁镀层的表面形貌及成分,使用X射线光电子能谱仪及电化学技术分析了锌铝镁镀层腐蚀产物的化学组成、电化学性能,对锌铝镁镀层的耐蚀机制进行了探讨,结果表明:锌铝镁镀层主要由初生锌相、富铝相及共晶组织组成,Mg元素主要分布于共晶组织中。在3.5%NaCl介质腐蚀过程中,锌镀层腐蚀产物主要由Zn₅(CO₃)₂(OH)₆及ZnO组成,锌铝镁镀层腐蚀产物主要由Mg(OH)₂、4MgCO₃·Mg(OH)₂及Zn₅(CO₃)₂(OH)₆组成。锌镀层腐蚀产物电荷传输电阻逐渐降低,而锌铝镁镀层腐蚀产物电荷传输电阻逐渐增大,且后者大于前者。即锌镀层腐蚀产物无法抑制镀层的腐蚀,而锌铝镁镀层腐蚀产物则可以对镀层电化学反应起到抑制作用,对镀层提供一定程度的保护。     

中国古青铜器表面富锡铜鎏镀及鎏焊的工艺探索 第二部分——鎏镀的原理及工艺设计

阐述了鎏镀料中铜、锡、铅、汞的主要作用,以及加热驱汞时各元素之间冶金反应的原理和物相变化。以仿古青铜镜为例,设计了 3 种鎏镀用富锡铜粉的配方,介绍了青铜件的镀前处理,汞齐涂料配制和涂抹的方法,以及加热驱汞的操作步骤。指出了古青铜器表面富锡镀层为鎏镀富锡铜的依据。     

硅和镁含量对双镀Zn–23Al镀层的组织结构和耐蚀性的影响第二部分──Zn–23Al–0.5Si–xMg镀层的组织结构和耐蚀性

采用"双镀法"在SPHC钢板表面热浸镀不同镁含量的Zn–23Al–0.5Si–xMg镀层(x=0.5,1.0,2.0,3.0).采用扫描电镜、能谱仪、显微硬度计以及电化学测试、中性盐雾试验等手段研究了浸镀液中镁含量对镀层组织结构、显微硬度和耐蚀性的影响.结果表明:随着浸镀液中镁含量升高,镀层表面块状富锌相逐渐细化,显微硬度增大,耐蚀性先改善后变差.浸镀液中Mg质量分数为2％时,镀层的耐蚀性最佳.     

烧结钕铁硼产品不合格镍/铜/镍镀层退除速率的研究

正0前言烧结钕铁硼是一种性能优异且性价比高的稀土永磁体,已广泛应用于电声器材、冶金工业、汽车制造、航空航天、医疗器械及微特电机等领域。烧结钕铁硼主要由Nd_2Fe_(14)B相、富Nd相和富B相组成。由于各相电位不同,所以在潮湿环境中会发生电化学反应,形成腐蚀原电池,造成晶间腐蚀~([1])。通常采用电镀或涂装等方法对烧结钕铁硼表面进行腐蚀防护~([2])。烧结钕铁硼在电镀镍/铜/镍镀层时,不可避     

γ相Zn-Ni合金镀层结构及性能分析

采用电沉积方法从碱性镀液中制备γ相Zn-Ni合金镀层,应用扫描电子显微镜、X-射线衍射仪、电化学测量技术对Zn-Ni合金镀层的微观结构和耐蚀性能进行了研究。结果表明,Ni-Zn合金镀层的腐蚀性与其微结构密切相关。Zn-Ni合金镀层的晶型为γ相,合金镀层中镍和锌的质量分数分别为15.98%和84.02%;锌-镍合金镀层中原子堆积方式为正四面体形。在5%氯化钠溶液中,γ相Zn-Ni合金镀层与锌镀层的电化学测试结果表明,在0-10Hz低频率区,γ-相Zn-Ni合金镀层的交流阻抗谱的实部值为镀锌层的7.2倍;腐蚀电位比锌层增加了0.1279V,镀锌层的Jcorr是γ相Zn-Ni合金镀层的5.78倍。     

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。     

铝合金化学镀镍层的制备及表征

利用化学沉积方法在铝合金表面制备镍-磷合金镀层。讨论工艺参数对合金镀层表面形貌、相结构及耐蚀性的影响。结果表明:温度对合金镀层表面形貌的影响较大,而对相结构的影响较小。在84℃下获得的合金镀层具有较好的耐蚀性。     

Microstructure and mechanical properties of Ti–C–TiN-reinforced Ni204-based laser-cladding composite coating

In situ Ti(C, N), ring phase, and multi-phase enhanced Ni204-based alloy coating were prepared by adding various Ti/C/TiN ratios particles. The effects of the reinforcement phase on the microstructure, microhardness, tribological property, and microstructure characteristics at the interface between the coating and substrate were investigated. The results show that the coatings with a 5:1 mass fraction ratio of TiN/C exhibits the highest microhardness, which is 3.78 times higher than that of the original Ni204 coating. While, the coating with 21:7:2 mass fraction ratio of TiN/Ti/C exhibits the lowest friction coefficient, which is 4.44 times smaller than that of the original Ni204 coating. The addition of Ti and C particles promotes the precipitation of ring phase and carbides, reduces ceramic agglomeration, alleviates the floating of ceramic particles, and improves the bonding strength of reinforcement phases. Owing to the good mutual solubility among Fe, Ni, and, Cr elements, the diffusion happened at the interface between the coating and substrate.     

Comparison of microstructure and mechanical properties of plasma-sprayed nanostructured and conventional yttria stabilized zirconia thermal barrier coatings

The main goal of this paper was to evaluate and compare the microstructure and mechanical properties of plasma-sprayed nanostructured and conventional yttria stabilized zirconia (YSZ) thermal barrier coatings (TBCs). To this end, NiCrAlY bond coat, nanostructured, and conventional YSZ coatings were deposited on Inconel 738LC substrate by atmospheric plasma spraying (APS). The mechanical properties of the coating were evaluated using nanoindentation and bonding strength tests. The microstructure and phase composition of the coating were characterized by field emission scanning electron microscopy (FESEM) and X-ray diffractometry (XRD). The nanostructured YSZ coating contained both nanosized particles retained from the powder and microcolumnar grains formed through the resolidification of the molten part of the powder, whereas the microstructure of the conventional YSZ coating consisted of columnar grain splats only. The phase composition of the as-sprayed nanostructured coating consisted of the non-transformable tetragonal phase, while the conventional coating showed the presence of both the monoclinic and non-transformable tetragonal phases. The results of nanoindentation and bonding strength tests indicated that the mechanical properties of the nanostructured coating were better than those of the conventional coating.     

连铸中间包涂料热负荷反应

采用X射线衍射仪、扫描电子显微镜和微区能谱分析等,研究了一种中间包涂料在使用后的显微形貌和物相组成变化,探讨了其变化的原因。认为中间包涂料在使用后生成了大量钙镁橄榄石等低熔点物质是导致涂料烧结严重的主要因素,并提出了生产中间包涂料时少加SiO2微粉以控制涂料热负荷反应的改进建议。     

等离子喷涂硅灰石涂层结构和性能的研究

采用等离子喷涂技术，在Ti-6Al-4V基体上制备了硅灰石涂层，利用SEM和XRD分析技术对涂层的形貌，结构和相组成进行了研究，按ASTMC－633标准对涂层的结合强度也进行了测试，将涂层试样浸泡于模拟体液中以评估其生物活性，利用SEM及配备的能谱仪（EDS），XRD和IR对浸泡后涂层表面产物的形貌，结构和相组成等进行了分析，结果表明，等离子喷涂硅灰石涂层具有粗糙的表面和层状结构，涂层内部存在一些气孔和微裂纹，涂层的主晶相是三斜晶系硅灰口，也存在玻璃相，硅灰石涂层和Ti-6Al-4V基体热膨胀系数相近，因此涂层和T-6Al-4V基体具有较高的结合强度，其值可达约39MPa，模拟体液浸泡试验显示，硅灰石涂层表面能形成含有碳酸根的羟基磷灰石层，这表明硅灰石涂层会有良好的生物活性，可作为生物活性涂层的候选材料。     

激光熔覆Zr65Al7.5Ni10Cu17.5非晶纳米晶复合涂层组织结构

在Ti基体上激光熔覆Zr65Al7.5Ni10Cu17.5合金粉末,得到含非晶、纳米晶复合涂层。分析表明涂层由金属间化合物和非晶、纳米晶构成。涂层按组织形貌分为3层:表面枝晶区、中部细晶区和结合区枝晶区。金属间化合物为Al2Zr3、CuZr2和Zr2Ni,纳米晶为简单四方Al2Zr3相,晶格常数为:a=b=7.618 nm,c=6.985 nm。     

等离子喷涂氧化锆涂层的显微结构分析

利用透射电镜(TEM)、扫描电镜(SEM)和X射线衍射仪(XRD)等分析技术,表征了等离子喷涂氧化锆涂层的显微结构.结果表明:等离子喷涂氧化锆涂层是由典型的柱状晶粒组成的层状结构;柱状晶粒晶型发育完整,晶粒之间具有清楚晶界;涂层表面存在明显的完全熔融区和未熔融区;涂层中分布有一定的大气孔.涂层的主晶相是四方氧化锆,没有单斜氧化锆相存在;涂层中裂纹的扩展是穿晶断裂和沿晶断裂共存.     

Relationship analysis on particle-coating-ablation property of UHTC coatings fabricated by plasma spray technique

The relative high porosity of plasma spray ultra-high temperature ceramic (UHTC) coatings has been an important limiting factor for the ablation property and one of the reasons is the original pores of feedstocks. In this work, dense and spherical ZrC–SiC powders were fabricated by induction plasma spheroidization (IPS) and were used to prepare ZrC–SiC coating by vacuum plasma spray. The effect of microstructure of feedstock particles on the microstructure and ablation property of coating was studied. The results showed that the spherodized particles were composed of eutectic-like phase and ZrC granules, exhibiting high degree of compactness and sphericity, which had higher deposition rate and generated splats with flattened structure to overlap compactly then produce highly dense coating compared with those of spray drying (SD) particles. The deposition rate was doubled and the porosity of the coating was reduced by half. The ablation resistance of ZrC–SiC coating was greatly improved due to the formation of dense oxide scale.     

Improved cohesion strength of plasma-sprayed TiCN coating by adding Ni and post annealing

In this work, the TiCN(15Ni) coatings were plasma-sprayed using the mixed Ti-graphite aggregates and Ni powders, and their microstructure evolution and cohesion strength after annealing at 200 °C, 400 °C and 600 °C were studied. The TiCN coating was plasma-sprayed with a lamellar structure and its phase compositions were TiC_0.7N_0.3, TiC_0.3N_0.7, Ti₂O, and residual graphite. For the TiCN–15Ni coating, besides the above phase compositions, metallic Ni phase was also detected. The addition of Ni could promote the reactions of Ti-graphite-N₂ system and make the microstructure compact. After annealing, the microstructure became more compact by crack-healing, internal stress decrease, and elemental diffusion. The cohesion strength of the TiCN coating was enhanced after adding Ni and post annealing at 400 °C and 600 °C, which was mainly because of the compact microstructure, toughening effect of the metal Ni, crack-healing and the decreased internal stress.     

Atmospheric plasma sprayed coatings of nanostructured zirconia

Nanostructured zirconia coating has been fabricated by atmospheric plasma spraying. The microstructure of the coating has been characterized with SEM and XRD, and the microhardness has been measured. The results show ZrO₂ coating possessed two kinds of structure. One was the poorly consolidatedly structure, which was composed of nanosized particles. The other was an overlapping structure, which consisted of micrometer size particles. The former was the main structure in the coating. The zirconia coating had the same phase composition as the starting powder and the thickness of coating was quite heterogeneous. The as-sprayed nano zirconia coating had a similar microhardness to sintered ZrO₂, which was much higher than the conventional couterpart.     

粉煤灰活性氩弧熔覆Al2O3-TiB2-TiC复合涂层组织和性能分析

以铁基合金粉末、Al、TiO2和B4 C粉末为涂覆材料,以高铝粉煤灰、SiO2、MgO、CaF2和CeO2为活性剂,采用活性氩弧熔覆技术在Q235钢表面原位合成Al2O3-TiB2-TiC颗粒增强铁基复合涂层.测试熔覆涂层的物相结构、金相组织、显微硬度和耐磨性能,并与未涂覆活性剂的常规熔覆涂层进行对比分析.结果表明,复合涂层由Al2O3、TiB2、TiC、FeSi2 Ti、FeB2和α-Fe相组成,其与基体界面无气孔、裂纹等缺陷,呈良好的冶金结合;复合涂层测试点的最高显微硬度为1283.4 HV0.2,其在室温干滑动磨损条件下耐磨性良好;粉煤灰复合活性剂的加入可以促进熔覆层与母材之间的良好熔合、增加涂层中新相种类和数目、提高氩弧熔覆效率,这对改善复合涂层的综合性能具有重要意义.