ZL104合金氩弧熔敷原位合成TiCp/Al基复合涂层组织及耐磨性

以Al粉、Ti粉和C粉为原料,利用氩弧熔敷技术,在ZL104合金表面原位合成了TiC增强Al基复合材料层,借助扫描电镜、X射线衍射仪对复合涂层的组织进行了分析;利用显微硬度计、摩擦磨损试验机对复合涂层性能进行了测试。结果表明,氩弧熔敷过程中可以充分反应合成TiC颗粒;TiC颗粒呈球状分布,颗粒尺寸约为1.5μm,均弥散分布于熔敷层中。熔敷层与基体呈冶金结合,无裂纹、气孔等缺陷;复合涂层的显微硬度可达660 HV0.2,涂层耐磨性较基体提高近7倍。     

氩弧熔敷原位合成TiC-TiB2/Ti基复合涂层组织及性能分析

利用氩弧熔敷技术,在TC4合金表面原位合成了TiC-TiB₂增强镍基复合材料涂层,利用SEM和XRD等方法分析了涂层的显微组织并测试了涂层的显微硬度.结果表明,熔敷组织主要由TiC,TiB₂和Ti(Ni,Cr)组成,TiB₂主要以棒状形式存在;在所形成的TiC-TiB₂/Ti复合材料层中,TiC和TiB₂颗粒分布均匀且尺寸细小;熔敷涂层由表及里组织不同;熔敷层与基体呈冶金结合,无气孔、裂纹等缺陷;涂层的显微硬度达到13.8 GPa,较基体提高了4.5倍.     

氩弧熔敷原位自生TiC_p/Ni60A金属基复合材料涂层的组织与性能

以Ni60A、Ti粉和C粉为原料,采用氩弧熔敷技术,在45钢表面原位合成了TiC增强Ni基复合材料涂层.借助扫描电镜、X射线衍射仪、显微硬度计对复合涂层的组织和性能进行了分析.结果表明,熔敷层与基体呈冶金结合,无裂纹、无气孔等缺陷;熔敷层的组织由γ-Ni、M23C6、TiC组成,TiC大部分旱块状,颗粒尺寸为1～1.5μm,均弥散分布于熔敷层中.     

原位自生TiC-TiB2增强Fe基复合涂层的凝固特性及形成机理

以Ti、B4C和Fe粉为原料,利用氩弧熔敷技术在Q235钢基体表面制备出原位自生TiC-TiB2增强Fe基复合涂层.利用扫描电镜(SEM)、X射线衍射仪(XRD)对涂层的显微组织进行了分析.并分析了TiC和TiB2颗粒的形成机理和氩弧熔池的凝固特性.实验结果表明:熔敷层组织为TiC和TiB2弥散分布在α-Fe中,熔敷层与基体呈冶金结合,无裂纹、气孔等缺陷;涂层中TiC和TiB2的体积分数约为68%.形成机理主要是以固态扩散机制为主,TiC以小颗粒状和花瓣状先析出,后析出的TiB2多以六边形、短棒状存在,TiB2的组织比较粗大,TiC颗粒比较细小,TiB2的含量大于TiC含量.     

35CrMnSi 表面氩弧熔覆原位自 生 TiC 复合涂层的组织及耐磨性

目的提高截齿的耐磨性,延长其使用寿命。方法利用氩弧熔覆技术在35CrMnSi钢表面制备TiC增强镍基复合涂层,分析涂层的显微组织和物相组成,测试涂层在室温下的显微硬度和耐磨性,并分析磨损机制。结果氩弧熔覆涂层的显微组织致密均匀,涂层与基体呈冶金结合,主要由TiC,γ-Ni,M23C6等物相组成。TiC颗粒呈块状,尺寸为1~2μm,弥散分布在涂层中。涂层硬度和耐磨性与(Ti+C)含量有关,熔覆粉末中(Ti+C)质量分数为20%时,涂层最高硬度可达1190HV,耐磨性达到基体的7.5倍。结论熔覆涂层的显微硬度较基体有显著提高。在室温冲击载荷作用下,熔覆涂层的主要磨损机制为显微切削磨损,可大大提高基体材料的耐磨性能。     

氩弧原位合成TiC颗粒增强Fe基复合层

通过在Fe基自熔合金粉末中添加一定比率的强碳化物形成元素Ti及石墨,采用氩弧熔敷法在中碳钢基体上制备原位形成的TiC颗粒增强Fe基合金复合涂层.利用扫描电镜、电子探针、X射线衍射和图像分析系统,对熔敷层显微组织及其影响因素进行了观察与分析.研究结果表明,利用氩弧熔敷技术,可以原位形成细小、弥散分布的TiC颗粒;TiC颗粒沿熔敷层深度呈梯度分布.通过调整预置涂层的厚度、熔敷工艺参数以及石墨的加入量,可以调整控制熔敷层的成形及组织与性能.     

Ti6Al4V合金表面氩弧熔覆原位合成TiC-TiB2增强钛基复合涂层组织与耐磨性

以B4C和Ni60A粉末为预涂材料,采用氩弧熔覆技术,在Ti6Al4V合金表面原位合成TiC与TiB₂增强相增强钛基复合材料涂层.运用XRD,SEM等分析手段研究了复合涂层的显微组织,利用显微硬度仪测试了复合涂层的显微硬度并用磨损试验机分析了其在室温干滑动磨损条件下的耐磨性能.结果表明,熔覆层组织主要由TiC和TiB₂组成,TiC颗粒和TiB₂颗粒弥散分布在基体上,TiC颗粒的尺寸为2~3μm,而呈长条状的TiB₂颗粒尺寸为3~5μm.显微硬度和耐磨性测试结果表明,该复合涂层显微维氏硬度高达1200MPa左右,复合涂层的耐磨性能比Ti6Al4V基体提高约20倍.     

氩弧熔敷原位自生TiCp/Ni60A复合材料组织和耐磨性

利用氩弧熔敷技术在16Mn钢表面原位合成TiC增强Ni基复合材料耐磨涂层.采用XRD、SEM等手段分析涂层的组织,测试涂层的室温干滑动磨损性能.结果表明:其室温干滑动磨损机制为显微切削磨损,熔敷层与基体呈冶金结合,TiC颗粒均弥散分布于熔敷层中.涂层有较高的硬度,在室温干滑动磨损试验条件下具有优异的耐磨性.     

氩弧熔敷原位自生TiC增强Ni基复合涂层的显微组织及工艺

采用MW3000型氩弧焊机在16Mn钢表面进行熔敷,原位生成TiC颗粒增强Ni基复合涂层.研究了氩弧焊接工艺参数(焊接电流、焊接速度、氩气流量)对熔敷层性能和质量的影响,利用SEM、XRD等手段对熔敷层显微组织和物相进行了研究.结果表明,氩弧焊接电流、焊接速度等工艺参数的合理匹配是原位生成TiC颗粒的关键因素.焊接电流为120 A、焊接速度为8 mm/s、氩气流量为10-12 L/min时能获得良好的性能及表面成形复合涂层.原位生成的TiC颗粒均弥散分布于熔敷层中,涂层的显微硬度可达1 100 HV.     

氩弧熔覆Fe基复合涂层的组织与性能

利用氩弧熔覆技术,以Ti粉、C粉、Fe粉为原料在Q235钢基体表面上原位合成高硬度复合涂层.采用金相显微镜观察分析涂层显微组织,利用洛氏硬度仪测试熔覆层的硬度.结果表明:熔覆层组织由树枝晶、等轴晶组成,TiC主要分布于晶粒内和晶界处,涂层显微硬度随TiC含量的增加而增大.     

Structural, mechanical and corrosion properties of TiOxNy/ZrOxNy multilayer coatings

Results on the deposition and characterization of TiO_xN_y/ZrO_xN_y multilayers, with bilayer periods of 20 and 400 nm, are presented. The coatings were deposited on TiNiNb alloy substrates by the pulsed magnetron sputtering method. The elemental composition, hardness, adhesion and corrosion resistance of the coatings were analyzed.As resulted from the XPS analysis, the individual layers consisted of a mixture of titanium or zirconium oxynitrides and corresponding oxides. X-ray analysis revealed that the coatings were amorphous. Only slight differences between the microhardness and adhesion values of the coatings with small and large bilayer period Λ were found. The experiments also showed that the multilayered coatings improved the corrosion resistance of the uncoated alloy and reduced the amount of ion release in artificial body fluids.     

生物医用NiTi形状记忆合金腐蚀研究进展

镍钛形状记忆合金(NiTi-SMA)具有较好的耐腐蚀和机械性能,在口腔和临床医学中有着大量而广泛的应用。NiTi-SMA腐蚀后释放Ni²⁺会引发细胞毒性和过敏反应,进一步提高NiTi-SMA的耐蚀性是目前生物医学材料领域发展的核心之一。本文对近年来国内外有关口腔医学和临床医学中常用NiTi-SMA的腐蚀研究现状进行了总结,同时也对NiTi-SMA增材制造及表面改性技术进行了评述,以期为开发高性能抗腐蚀生物医用NiTi-SMA提供一定的指导意义。     

Li掺杂Ba(Ti1/7Sn1/7Zr1/7Hf1/7Nb1/7Ga1/7Li(1/7-x))O3高熵陶瓷的制备及介电性能研究

近年来,在高熵合金基础上发展起来的高熵陶瓷逐渐引起了研究者的广泛关注,其出现为开发高性能的无机非金属材料提供了新的设计思路。本文采用固相法制备了BaMO3基钙钛矿型高熵陶瓷Ba(Ti1/7Sn1/7Zr1/7Hf1/7Nb1/7Ga1/7Li(1/7-x))O3 (x = 0, 2.3%, 5.3%, 8.3%, 11.3%),并研究了Li含量对高熵陶瓷物相结构、微观形貌及介电性能的影响。结果表明,Li含量对陶瓷结构的影响不大,陶瓷均保持立方钙钛矿结构,且无杂相产生;陶瓷的晶粒尺寸相对较均匀。当x = 0时,即B位七元等摩尔比Ba(Ti1/7Sn1/7Zr1/7Hf1/7Nb1/7Ga1/7Li1/7)O3高熵陶瓷,其介电常数达到了最大值2920 (@100 Hz),相较于已报道的不掺Li的六元高熵钙钛矿陶瓷Ba(Ti1/6Sn1/6Zr1/6Hf1/6Nb1/6Ga1/6)O3提升了近50倍。     

MOCVD growth and characterizations of BxAl1−xAs and BxAl1−x−yInyAs alloys

Zinc-blende B_xAl_1−xAs and B_xAl_1−x−yIn_yAs alloys have been grown on exactly oriented (0 0 1)GaAs substrates by low pressure metalorganic chemical vapor deposition (LP-MOCVD). The influence of susceptor coating, growth temperature and gas-phase boron mole fraction on boron incorporation into AlAs has been comprehensively investigated. It has been found that boron incorporation into AlAs could be enhanced and the optimal growth temperature range of B_xAl_1−xAs alloys changed from 580 °C to 610 °C when SiC-coated graphite susceptors were replaced by the non-coated ones. In this study, the maximum boron composition x of 2.8% was achieved for the pseudomorphically strained B_xAl_1−xAs alloys. AFM measurements show that RMS roughness of B_xAl_1−xAs alloys increased sharply with the increase of gas-phase boron mole fraction. Raman spectra of B_xAl_1−xAs alloys show a linear increase of the BAs shift with boron composition x. Based on BAlAs deposition, bulk B_xAl_1−x−yIn_yAs (x = 1.9%) quaternary alloy was grown lattice-matched to GaAs successfully. Moreover, 10-period BAlAs/GaAs and BAlInAs/GaAs MQW heterostructures were also demonstrated.     

Hydrothermal synthesis of superconductors Ba1−xKxBiO3 and double perovskites Ba1−xKxBi1−yNayO3

Superconductors Ba_1−xK_xBiO₃ and body-centered double perovskites Ba_1−xK_xBi_1−yNa_yO₃ have been selectively synthesized by a facile hydrothermal route. The appropriate ratio and adding sequence of initial reagents, alkalinity, reaction temperature and time are the critical factors that influence the crystal growth of the compounds. The purity and homogeneity of the crystals were detected by the ICP, SEM, EDX and TEM studies. Magnetic measurements show that the superconducting transition temperatures T_C of Ba_1−xK_xBiO₃ decrease from 22 K (for x = 0.35) to 8 K (for x = 0.55) with increasing the K doping level.     

Magnetic phase diagrams of the TbRh2−xPdxPdxSi2 and TbRu2−xPdxSi2 systems

The a.c. susceptibility and high field magnetization on TbRh_2−xPd_xPd_xSi₂ and TbRu_2−xPd_xSi₂ compounds were investigated up to 140 kOe. The (T,x) magnetic phase diagrams were determined. For both systems, an increase in the Pd content causes a decrease in the Néel temperature and changes the magnetization curves.     

High strength and good ductility of casting Al-Cu alloy modified by PrxOy and LaxOy

A modified Al-Cu alloy with high tensile strength and ductility of about 574.0 MPa and 10.4%, respectively, was obtained by adding multiple rare earth oxides (Pr_xO_y and La_xO_y) as modifier. Compared with the unmodified Al-Cu alloy, the tensile strength and ductility of the modified sample were increased by 24.3% and 42.5%, respectively. The improvement both in the strength and ductility may attribute to the finer crystal grains and dendrites, more homogeneously distributed θ′ phase precipitates and the intermetallic compounds formed at the crystal grain boundaries as well as in the space of the dendrites.     

Structural analysis of sputtered (W-C)1−xMx (MFe, Co) films with 0x0.20

Structural characterization of (W-C)_1-xM_x (MFe, Co) films with 0x0.20 was carried out using electron probe microanal ysis (EPMA), X-ray diffraction (XRD) and transmission electron microscopy-electron diffraction (TEM-ED). The results showed that the structure of these films depends on the percentage of iron and cobalt and becomes amorphous with increasing content of these elements. The microstructure of the crystalline coatings was found to be composed of small grains of β-WC_1-x with a high number of defects. A strong β-WC_1-x[311] texture was observed for iron and cobalt contents around 5.5 at.%. The films richer in iron and cobalt showed typical amorphous XRD and ED patterns, exhibiting two broad peaks and two wide diffuse rings respectively. Moreover, bright-field analysis revealed fairly contrasted images, the structure of these films being difficult to resolve.     

Si3N4/Ti/Cu/Ni/Cu/Ti/Si3N4二次部分瞬间液相连接强度

采用Ti/Cu／Ni中间层对Si3N4陶瓷进行二次部分瞬间液相(PTLP)连接，研究连接工艺参数对Si3N4／Ti/Cu／Ni连接强度的影响，同时研究了连接强度随试验温度的变化规律。结果表明，在该试验条件下，室温连接强度随着二次连接温度的提高和二次保温时间的延长而提高，改变连接工艺参数对Si3N4／Ti/Cu／Ni二次PTLP连接界面反应层厚度无明显影响；连接强度在试验温度400℃时达到最大，随后随试验温度升高，连接强度降低，但在800℃前，其高温强度具有很好的稳定性。