激光熔覆Fe基非晶／纳米晶复合涂层的组织与性能

对以激光熔覆方式在45钢基体上制备的FeNiSiBVRE非晶涂层进行激光晶化,制备非晶／纳米晶复合涂层,利用X射线衍射仪、透射电镜、扫描电镜和磨损试验机研究非晶／纳米晶复合涂层的组织与性能,研究结果表明,涂层存在着分层结构,组成相有晶化相、非晶相和纳米晶相;涂层底部和顶部的显微组织由大量的稀土树枝晶、板条状硼化物和粒状碳化物组成,涂层中部的显微组织是由大量的纳米晶相镶嵌在非晶基体上构成,与没有进行激光晶化的非晶涂层相比,涂层的耐磨损性能下降,其磨损机制以粘着磨损和剥层磨损为主。     

激光熔覆复合涂层的研究进展

激光熔覆是一门新兴的表面涂层技术，发展迅速．本文系统地总结了激光熔覆的工艺特点，对激光熔覆复合涂层的材料体系、组织特征进行了综合分析，指出了存在的问题及今后的研究方向．     

钢表面激光熔覆TiCp／Fe基合金复合耐磨涂层

在２０钢表面用激光束熔覆了ＴｉＣ颗粒与Ｆｅ基自熔合金复合耐磨涂层。对涂层的组织、化学成分、硬度及耐靡性进行了分析、结果表明。熔覆层主要由γ－Ｆｅ，α－Ｆｅ和ＴｉＣ颗粒组成。     

Fe基非晶软磁合金的纳米晶化及磁性

研究了Fe78Si9B12,Fe73.5Cu1Nb3Si13.5B9,Fe74Cu1Mo2Nb1Si13B9三种非晶软磁合金在753-853K温度间等温退火lh后的纳米晶化行为和磁性，实验证明Cu，Nb和Mo元素的加入有助于提高晶化温度，稳定非晶组织．同时采用差热分析和X衍射仪分析了三种合金的晶化相，测量了其磁滞回线，结果表明l^#，2^#，3^#合金分别在753K，813K，753K退火lh后可获得优良的综合软磁性能。     

激光熔覆钛基复合涂层的显微组织和硬度分析

采用激光熔覆快速非平衡合成方法制备了原位反应合成TiB增强钛基复合材料.用Y2O3、Ti和B的混合粉末在Ti-6Al-4V基体表面激光熔覆制得TiB/Ti复合涂层.采用X线衍射仪(XRD)、扫描电子显微镜(SEM)、能量散射光谱仪(EDS)和硬度测试等方法,研究了原位合成TiB/Ti复合涂层的显微结构和显微硬度.结果显示:激光熔覆层的相结构主要为α-Ti和TiB两相,TiB增强相均匀地分布于复合涂层中,熔覆层的硬度值高于基体Ti合金的硬度值1倍以上,Y2O3含量(质量分数w,全文同)为1％的激光熔覆涂层内部的增强相组织最为均匀、细小,且硬度值也最高,平均硬度(HV)值约为830.     

激光熔覆Fe+B4C复合涂层的组织及耐磨性

利用激光器在SPHC钢基材表面激光熔覆w(B4C)=5%的Fe基复合涂层(Fe B4C),对熔覆层的组织形貌及耐磨性进行分析,并与铁基合金涂层(Fe55)作对比研究.结果表明,Fe55熔覆层主要为有明显方向性的柱状枝晶组织,由α-Fe枝晶固溶体与枝晶间共晶组织(α-Fe Cr23C6)组成;加入B4C后,改变了铁基熔覆层的凝固特征,Fe B4C熔覆层主要由组织均匀、无明显生长方向性的α-Fe杆状枝晶固溶体与其间的共晶组织组成,共晶化合物相明显增多,主要有Fe2B,CrB,Cr23C6,Cr7C3,Fe3(B,C)等.Fe B4C复合涂层的硬度及耐磨性比Fe55涂层明显提高.     

Fe75Cr12.5Mo12.5合金非晶/纳米晶化过程的分子动力学模拟

为模拟Fe75Cr12.5Mo12.5合金非晶/纳米晶化的整个过程,采用分子动力学方法,通过动力学弛豫、淬火和退火处理得到了Fe75Cr12.5Mo12.5合金的非晶/纳米晶态结构.采用径向分布函数(radius distribution function,RDF)和X线衍射图(X-ray diffraction,XRD),分析了模拟过程中各阶段的原子结构.结果表明:Fe75Cr12.5Mo12.5合金的非晶和纳米晶形成能力较强,添加非金属元素能进一步提高非晶形成能力.分子动力学模拟技术为铁基非晶/纳米晶的成分配比和工艺选择提供了理论依据.     

模具钢的激光熔覆组织和性能

利用不同的激光工艺参数对Cr12MoV模具钢表面进行熔覆试验,探讨了工艺参数对熔覆层深度的影响,研究了表面微观硬度的趋势及其原因、熔覆层耐磨性能的提高幅度以及组织结构的变化。结果表明：表面硬度在不同程度上都得到提高,硬度峰值出现在次表层;激光熔覆层的耐磨性能可以提高到1．91－4．24倍;微观结构由平面晶和枝晶构成的共晶组织,并有多种合金相分布在枝晶间。     

激光熔覆TiCp／Ni基自熔合金复合耐磨涂层的组织

在４５钢表面激光熔覆３０％ｖｏｌＴｉＣｐ－Ｎｉ基自熔合金复合耐磨涂层，其组织由ＴｉＣ颗粒，γ－Ｎｉ与Ｃｒ２３Ｃ６型碳化物的共晶及γ固溶体枝状初晶组成。因冷却速度的差异，在涂层的不同部位分别得到了典型的花瓣状和规则六边形ＴｉＣ颗粒。ＴｉＣ颗粒与γ－Ｎｉ基体有一定的取向关系。     

激光熔覆（WC＋SiC）／Ni基复合涂层中合金元素的分布

利用２ＫＷ的ＣＯ２激光器的１６Ｍｎ钢表面激光熔覆（ＷＣ＋ＳｉＣ）／Ｎｉ基复合涂层，经ＳＥＭ及ＥＤＸ能谱分析表明，基体与涂层呈良好的冶金结合。承着凝固过程的进行，γ－Ｎｉ固溶体的形貌由平面晶发展为树枝晶，且γ－Ｎｉ固沉吟体间合金元素的含量及平面晶的厚度均随机扫描的变化而变化。     

温度控制Fe基合金带纳米微晶生长技术的研究

研究了Fe73.0CuNb1.5V2Si13.5B9非晶带经不同温度（480℃、510℃、540℃、570℃）退火而长成的纳米微晶薄带的软磁特性,发现540℃是其最佳退火温度,经该温度退火可获得最高的巨磁阻抗效应。     

脉冲电沉积Ni-SiC复合镀层的组织形貌与性能研究

利用直流(DC)和脉冲(PRC)两种电沉积方法制备了Ni-SiC复合镀层.利用X射线衍射仪(XRD)检测了镀层的微观结构与性能,通过扫描电镜(SEM)观察了镀层的表面形貌.结果表明:脉冲方法得到的纯镍镀层和复合镀层结晶晶粒更细小均匀,表面更致密平整.当镀层中SiC含量约为10.6%时脉冲镀层的宏观残余应力较直流镀层降低19.5%,硬度提高6.6%.     

Microstructure and tribological properties of laser clad Ni-Ag/Tic composite coating

Ni-Ag/TiC composite coating was prepared on the 45 steel substrates by means of laser cladding. Microstructure and wear properties of composite coatings were analyzed using optical microscopy, field emission scanning electron microscopy and wear machine. The experimental results show that defects, such as cracks and pores, do not occur in the laser-cladded Ni-Ag/TiC composite coating and 45 steel substrate, and they present good metallurgical bonding between them. Compared with Ni/TiC composite coating, micro- hardness values of the two coatings do not present evident differences. The wear experiment result shows that Ni-Ag/TiC composite coated with Ag possesses low friction coefficient and good wear resistance compared with Ni/TiC composite coating.     

聚苯胺／氟碳乳液复合涂层的防腐蚀性能

以聚苯乙烯磺酸（PSSA）为掺杂剂,制备水性聚苯胺（PANI）-蒙脱土（MMT）复合材料,再以水性氟碳乳液（FC）为成膜物,制备水分散体PANIL氟碳乳液复合涂层材料用于A3钢的防腐蚀。利用平衡开路电位（OCP）、电化学交流阻抗谱（EIS）、Tafel曲线考察了掺杂剂和蒙脱土对防腐蚀性能的影响。XRD结果表明PANI—MMT复合材料中的蒙脱土以片层剥离状态存在;当n（PSSA）：n（An）=1．5：1和m（An）：m（MMT）=1：2．5时,复合涂层具有较高的阻抗,显著提高了金属的腐蚀电位（-0．75V）,降低了金属的腐蚀电流密度（10^-7.5A／cm^2）。     

铁基块体非晶合金的研究进展

概述了铁基块体非晶合金的发展,简要介绍了合金元素对玻璃形成能力的影响、铁基块体非晶合金的主要制备方法及各种独特性能,并对铁基块体非晶合金的研究方向进行了展望.     

仿生凹坑与纳米碳化硅/镍基复合镀层耦合表面的磨损性能

为了探讨凹坑形态与纳米碳化硅/镍基复合镀层耦合表面的磨损性能,采用激光技术和电沉积技术制备了由凹坑形态和纳米碳化硅/镍基复合镀层构成的仿生耦合表面,并进行了摩擦和磨损试验。结果表明,仿生耦合表面的磨损性能高于单纯复合镀层的磨损性能;随着磨损载荷的增加和磨损时间的延长,试样表面磨损机制由以塑性磨损为主逐渐转变成以粘着磨损、磨粒磨损为主的磨损机制。     

镍、磷和空心微珠复合镀层摩擦磨损性能研究

运用化学镀方法,把空心微珠作为第二相加入化学镀镍和磷镀液中,制得以镍、磷和空心微珠为主的复合镀层.X射线分析显示,复合镀层经过热处理后由非晶态变成晶态.复合镀层经过热处理后显微硬度及摩擦学性能提高.复合镀层耐磨性比纯镍和磷镀层提高约30%,抗腐蚀性提高77%.运用SEM和XPS等对复合镀层性能和结构进行分析.     

Microstructure and properties of sputtered thermal barrier coatings

A 3 kW radio frequency (RF) magnetron-sputtering unit was used to produce zirconia ceramic coatings on hollow turbine blades and vanes, which had been deposited a NiCrAlY bond coat layer by cathodic arc deposition. The NiCrAlY coating surface was shot-peened, and the residual stress in the bond coat layer and the effects of heat treatment on the residual stress are presented. After shot peening porosities and microgaps disappear in the NiCrAlY bond coat, the whole depth profile is residual compressive stress. Coarseness tests show that the roughness value (Rz) decreases from 16.4 to 3.3 μm. The microstructure and phase composition of the coatings were investigated using electron probe microanalysis (EPMA) and X-ray diffraction (XRD). The results show that tho/NiCrAlY bond coat is composed of γ and Cr phases, and the Al2O3 scales are formed near the interface between the ZrO2 ceramic layer and the NiCrAlY bond coat. No degradation occurred to RF sputtered ceramic coatings after oxidating at 1150℃ for 100 h, heating at 1150℃ for 5 min and then air-cooling for 500 thermal cycles.     

Crystallization kinetics of amorphous Nd3.6 Pr5.4 Fe83Co3B5 and preparation of α-Fe/Nd2Fe14B nanocomposite magnets by controlled melt-solidification technique

The crystallization kinetics of amorphous Nd3. 6 Pr5.4 Fe83 Co3 B5 and the preparation of α-Fe/Nd2 Fe14 B nanocomposite magnets by controlled melt-solidification of Nd3.6Pr5.4Fe83Co3B5 was investigated by employing DTA, XRD, and TEM. The results show that a metastable intermediate phase Nd8Fe27B24 prior to α-Fe and Nd2 Fe14 B phases is crystallized as the amorphous Nd3.6 Pr5.4 Fe83 Co3 B5 is heated to 1 223 K. The crystallization activation energy of α-Fe and Nd8 Fe27324 phases is larger at the beginning stage of crystallization, and then it decreases with crystallized fraction x for the former and has little change when x is below 70% for the latter, which essentially results in an α-Fe/Nd2 Fe14 B microstructure with a relatively coarse grain size about 20-60 nm and a non-uniform distribution of grain size in the annealed alloy. The a-Fe/Nd2 Fe14 B nanocomposite magnets with a small average grain size about 14 nm and a quite uniform grain size distribution were prepared by controlled melt-solidification of nealing the amorphous Nd3. 6 Pr5. 4 Fe83 Co3 B5 precursor alloy.     

Microstructure and mechanical properties of an in situ synthesized TiB and TiC reinforced titanium matrix composite coating

A titanium-based composite coating reinforced by in situ synthesized TiB and TiC particles was fabricated on Ti6Al4V by laser cladding. The microstructure and mechanical properties were investigated. The coating was mainly composed of β-Ti cellular dendrites and an eutectic in which a large number of rod/needle-shaped TiB and a few equiaxial TiC particles were homogeneously embedded. The microstructural evolution could be divided into four stages: precipitation and growth of primary β-Ti phase, formation of the binary eutectic β-Ti+TiB, formation of the ternary eutectic β-Ti+TiB+TiC, and solid transformation from β-Ti to β-Ti. Microhardness of the coating showed a gradient variation from the surface (about HV0.2 876) to the bottom (about HV0.2 660) and was prominently improved in comparison with that of the substrate. Fracture toughness of the coating also exhibited a gradient variation from the surface (6.3 MPa·m1/2) to the interface (11.9 MPa·m1/2). Wear resistance of the coating was significantly superior to that of Ti6Al4V.