真空热压温度对等离子喷涂涂层性能的影响

为提高钢材表面等离子喷涂涂层的性能,利用真空热压工艺对原始涂层进行处理,通过对比涂层内部结构、结合强度、显微硬度、摩擦性能,分析真空热压工艺对等离子喷涂涂层性能的影响。结果表明,经过热压处理后,离子喷涂涂层内部组织致密均匀,摩擦损失量变小,基体与涂层结合强度与平均显微硬度均增大,摩擦性能得到提升,改善了离子喷涂涂层的整体性能。     

纳米颗粒粒径对等离子喷涂法制备氧化锆纳米涂层的影响

利用扫描电镜(SEM)、场发射扫描电镜(FESEM)、透射电镜(TEM)、比表面积吸附法(BET)等分析测试技术,研究了3种不同纳米尺寸氧化锫粉粒的造粒性能、沉积效率以及对等离子喷涂涂层晶粒大小、涂层熔融性能、结合强度的影响.结果表明:纳米氧化锆粉体一次颗粒粒径大小显著影响纳米粉体的喷雾造粒性能、沉积效率、涂层表面粗糙度、涂层晶粒粒径和结合强度大小.本试验中,利用颗粒一次粒径范围为50～70 nm的纳米氧化锆粉体,等离子喷涂制备了晶粒粒径范围为80～120 nm,沉积效率为43%,涂层表面粗糙度为5.92 μm,结合强度为27 MPa的纳米结构氧化锆涂层.     

纳米稀土对超音速火焰喷涂WC-10Co-4Cr涂层的改性研究

利用超音速火焰喷涂技术在45~#钢上制备了3种不同纳米稀土含量的WC-10Co-4Cr涂层,通过X射线衍射仪和扫描电镜对涂层进行物相成分及组织形貌进行分析,测定了涂层的孔隙率、结合强度、显微硬度和电化学腐蚀性能,研究纳米稀土对WC-10Co-4Cr涂层的改性作用。结果表明:适量纳米稀土的加入会使WC-10Co-4Cr涂层的孔隙率显著降低,结合强度和显微硬度大幅度地提高,且掺入纳米稀土改性剂可以有效地抑制WC颗粒的氧化脱碳,细化组织结构,净化晶界,提高涂层的耐腐蚀性能。     

电热爆炸超高速喷涂原位合成碳化钼陶瓷涂层的实验研究

利用电热爆炸超高速喷涂技术在45#钢基体上原位合成碳化钼陶瓷涂层试样,利用X衍射(XRD)、扫描电镜(SEM)、能谱仪(EDS)和显微硬度计对涂层的成分、显微组织和显微硬度进行了分析.结果显示涂层组织致密,空隙率低,没有分层现象,涂层和基体之间形成了冶金结合.XRD显示涂层中主要是原位合成的Mo2C、MoC和.Mo相,没有氧化物的生成.涂层中形成的碳化钼陶瓷相,具有弥散强化的作用,提高了涂层的硬度.     

高分散性纳米氧化锆晶粒在涂料中的应用

利用非水合成方法得到的高分散性纳米氧化锆(zrO2)晶粒为原料,经甲基丙烯酰氧基丙基三甲氧基硅烷(MPS)改性后,与紫外光固化涂料混合,荻得纳米复合涂料.实验发现,纳米复合涂层存在从透明性向不透明性转变的临界ZrO2浓度,此浓度值强烈依赖于有机相的组成和MPS在纳米ZrO2粒子表面的接枝量.在ZrO2临界浓度以下,纳米复合涂层的折射率,显微硬度、热稳定性随着纳米ZrO2用量的增加而提高;但ZrO2浓度高时,由于双键转化率的降低以及有机相-无机相之间界面作用力的减小,其各项性能开始明显恶化.     

脉冲电沉积纳米晶Zn涂层的结构表征与摩擦学性能

采用脉冲电沉积法,通过调节电流密度控制涂层的晶粒尺寸,在铜基体上制备了平均晶粒尺寸为6~32 nm的Zn涂层,采用XRD, SEM和显微硬度、摩擦实验等手段,表征了涂层的微观结构,并研究了其力学性能与摩擦学性能. 结果表明,纳米晶Zn涂层的表面平整致密,平均晶粒尺寸随电流密度增大而减小,随着晶粒尺寸减小,涂层的显微硬度增大,摩擦系数降低. 当电流密度从0.3 A/cm2增大至2.4 A/cm2时,平均晶粒尺寸从32 nm下降为6 nm,显微硬度从低于0.5 GPa增大至2.0 GPa以上,在大气环境中与Si3N4球之间的滑动摩擦系数从0.18降低至0.05. 硬度随晶粒尺寸的变化规律符合经典的Hall-Petch关系.     

La2O3对激光热喷涂TiC增强Al基涂层组织与性能的影响

运用激光热喷涂技术在S420钢表面制备了TiC增强Al基涂层,采用扫描电镜、X射线衍射仪、维氏硬度计和电化学工作站表征了涂层的显微组织、物相、显微硬度和耐蚀性.结果表明:涂层主要由基体Al相、连续相和硬质TiC增强相组成,涂层与基体界面间为冶金结合.添加适量的La2O3可以细化涂层内晶粒,提高涂层的显微硬度和耐蚀性.     

TiC添加量对等离子熔覆Ni60–WC复合涂层性能的影响

在45钢上通过等离子熔覆制备了WC?TiC?Ni涂层,对其物相、显微硬度和滑动摩擦磨损行为进行了分析.结果表明:熔覆层与基体材料之间为冶金结合,熔覆层表面无裂纹和气孔.TiWC2的形成使得熔覆层的显微硬度和耐磨性得到提高.当TiC的添加量为20％(质量分数)时,涂层的平均显微硬度高达1072.5 HV,较WC/Ni熔覆层高了128 HV,此时涂层的耐磨性最好.     

超音速等离子喷涂MoWCu合金涂层的性能

采用超音速等离子喷涂技术在45CrNiMoVA钢表面制备了MoWCu合金涂层。利用场发射扫描电镜、能谱仪、X射线衍射仪、维氏显微硬度计和球-盘式摩擦磨损试验机考察了涂层的形貌、成分、显微硬度和耐磨性,采用四探针法测量其导电性。MoWCu涂层的显微硬度平均值为486.2 HV0.1,比基体硬度提高1倍,与纯Mo涂层的显微硬度相当,但比MoW涂层的显微硬度略低。MoWCu涂层与基体的结合强度为45.3 MPa,表现为机械结合。MoWCu涂层的导电率为8.83%IACS,比纯Mo涂层高2/5左右。与纯Mo涂层和MoW涂层相比,在相同摩擦条件下,MoWCu涂层的磨损体积最小,摩擦因数最低,主要以粘着磨损为主,同时伴有轻微的氧化磨损。     

等离子熔覆WC复合厚涂层特性研究

将Ni基合金和Ni包WC粉末混合均匀后事先涂覆在低碳钢基体上，通过非压缩弧等离子熔覆设备在低碳钢上制备Ni包WC复合厚涂层。涂层分为三种重量百分比Ni包WC粉末，分别为5％，10％，15％。应用X衍射（XRD）、光学显微镜（OM）、扫描电镜（SEM）、能谱仪（EDS）和显微硬度分析对涂层成分、微观结构和显微硬度进行分析。结果显示涂层和基体之间形成冶金结合，XRD显示主要的相是γ-Ni周溶体，以及Fe2B、Fe3B相和M23C6、M7C3相。发现等离子熔覆区的显微硬度随着Ni包WC粉末含量的增加而提高。     

Preparation of interpenetrating alumina–copper composites

To prepare interpenetrating alumina–copper composites, alumina foams were activated with titanium coating by chemical vapor deposition and then were infiltrated with molten copper by expendable casting process. The microstructure and phase composition of the composites were analyzed, and bending strength, electrical conductivity, friction and wear properties were tested. The results showed that the bonding between ceramic and metal was fine in the composites while no reactions took place between them because of the undissolved titanium coating. With increase of ceramic fraction, the electrical conductivity of the composite decreased, whereas the bending strength increased. The composite failure occurred by ductile fracture of the metal followed by fracture of the ceramic. The wear rate of the composites decreased with increase of ceramic fraction. And the wear of the composites was featured with ceramic struts peeling compared with ploughing and adhering wear for pure copper.     

TiB2防护涂层的制备及性能

太阳能热发电一体化系统具有储热密度高、发电效率大、无污染等特点.为了提高太阳能热发电中容器的使用寿命,本文中在310S不锈钢容器内壁制备了TiB2防护涂层,并对涂层的主要抗热震性能、力学性能和对熔融态储能材料Al-12.07％Si的耐蚀性能进行了分析.结果表明:TiB2涂层抗热震性能好,涂层与基体结合强度较高;同时涂层在一定温度下具有较好的耐蚀性,从而延长容器的使用寿命.     

Microstructure and bioactivity in SBF of the hydroxyapatite coatings plasma sprayed with a magnetic field

A 100 mT magnetic field was introduced during the plasma spraying of hydroxyapatite (HA) coating on Ti6Al4V substrate. The influence of the magnetic field on the microstructure, bonding strength, and bioactivity of the coating was investigated. Compared with as-sprayed coating, the coating sprayed under a magnetic field showed fewer porosity and microcracks and a significantly decreased absolute value of the residual stress. The bonding strength of the coating sprayed under a magnetic field was approximately 173.6 % greater than as-sprayed coating. With increasing time in simulated body fluid, the width of microcracks on the surface of both coatings first increased and then decreased. The widths of microcracks on the coating sprayed under a magnetic field were much smaller than as-sprayed coating. During spraying process, the magnetic field would enhance the wetting and flowing ability of the HA molten droplets, prolonging their cooling, which affects the microstructure and bioactivity of the coating.     

超声机械镀铜的性能研究

利用超声机械镀实验装置制备了性能良好的铜镀层,借助扫描电子显微镜及能谱仪,分析铜镀层的外观、结合强度、表面形貌及化学组成,并对镀铜层抗腐蚀性能进行测试。结果表明,超声机械铜镀层色泽均匀且致密,与基体结合强度良好,耐腐蚀性提高。     

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.     

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.     

电泳沉积用羟基磷灰石稳定悬浮液的制备

研究了羟基磷灰石粉体粒径、粉体预烧温度、陈化时间、分散溶剂、悬浮液固含量对羟基磷灰石悬浮液稳定性的影响,通过测定Zeta电位,吸光度等参数表征悬浮液稳定性,对悬浮液电泳沉积的涂层进行SEM表面形貌及粘结-拉伸结合强度的表征.结果表明:悬浮液颗粒越小,Zeta电位越高;对羟基磷灰石粉体预烧800℃,Zeta电位明显提高,且有利于涂层与基体的结合;悬浮液陈化48 h后,颗粒荷电性最佳,可得致密均匀的涂层;以乙二醇为分散溶剂可制备稳定的悬浮液,但乙醇溶剂更有利于涂层的电泳沉积;悬浮液固含量控制为20g/L时,涂层质量较好.     

Bonding strength and thermal shock resistance of a novel bilayer (c-AlPO4-SiCw-mullite)/SiC coated carbon fiber reinforced CMCs

Mullite coating, SiC whiskers toughened mullite coating (SiC_w-mullite), and cristobalite aluminum phosphate (c-AlPO₄) particle modified SiC_w-mullite coating (c-AlPO₄-SiC_w-mullite) were prepared on SiC coated C/SiC composites using a novel sol-gel method combined with air spraying. Results show that molten SiO₂ formed by the oxidation of SiC whiskers and molten c-AlPO₄ improved the bonding strength between mullite outer coating and SiC–C/SiC composites due to their high-temperature bonding properties. The bonding strength between mullite, SiC_w-mullite, c-AlPO₄-SiC_w-mullite outer coatings and SiC–C/SiC composites were 2.41, 4.31, and 7.38 MPa, respectively. After 48 thermal cycles between 1773 K and room temperature, the weight loss of mullite/SiC coating coated C/SiC composites was up to 11.61%, while the weight losses of SiC_w-mullite/SiC and c-AlPO₄-SiC_w-mullite/SiC coatings coated C/SiC composites were reduced to 7.40% and 5.12%, respectively. The addition of appropriate SiC whiskers can considerably improve the thermal shock resistance of mullite coating owing to their excellent mechanical properties at high temperature. In addition, c-AlPO₄ particles can further improve the thermal shock resistance of SiC_w-mullite coating due to their high-temperature bonding and sealing properties. No obvious micro-pores and cracks were observed on the surface of c-AlPO₄-SiC_w-mullite coating after 48 thermal cycles due to timely healing effect by formation of secondary mullite.     

数控超声机械镀设备的开发

开发了数控超声机械镀设备,包括数控平台和超声装置,结合插补算法,提出了一种新型机械镀工艺,解释了设备独特的设计原理和全新的设计方法。利用开发的设备进行超声机械镀试验,镀层厚度用测厚仪测量,镀层和基体的结合强度利用划痕法测试。结果表明,数控超声机械镀设备运行状态稳定且良好,操作简易方便。通过改变数控机床运行速度与运动轨迹,调节超声波发生器的频率与功率,可以改变工件表面镀层质量及厚度。镀层表面光亮、平滑且结合强度良好,达到了预期目的。     

Hot-melt adhesion and wettability between polyethylene and other polymers in the vicinity of the adherend melting point

The effect of bonding temperature on the bonding strength of polyethylene to polypropylene or other polymers was investigated. It became clear that the interfacial bonding strength reached maximum strength at a bonding temperature in the vicinity of the melting point of the adherend (i.e., the polymer having the higher melting point). The effect of temperature on the contact angle of the molten polymer having the lower melting point on the adherend surface was also investigated. The wettability of the adherend by the molten polymer drop was considerably reduced at the temperature near the melting point of the adherend. The relationship of increasing adhesiveness to decreasing wettability was found out.