氩弧熔覆原位合成TiN复合涂层的组织与耐磨性

为提高钢材料的耐磨性,以Ti、TiN和Ni60A三种粉末作为涂层材料,采用氩弧熔覆、原位合成技术,在Q235钢表面制备TiN复合涂层.利用扫描电镜（SEM）、X射线衍射仪（XRD）、显微硬度计及滑动磨损实验机（MMS-2B）对复合涂层的显微组织结构、硬度和耐磨性进行分析.结果表明：涂层主要由TiN和α-Fe组成,TiN分布均匀且与基体呈现冶金结合,涂层显微硬度最高达738.17 GPa,耐磨性为Q235钢的8倍.涂层在室温干滑动摩擦磨损条件下表现出优异的耐磨损性能,具有应用价值.     

TC4合金氩弧熔覆TiN复合涂层的组织及耐磨性

为提高钛合金表面性能,以TiN粉和Ti粉为原料,利用氩弧熔覆技术,在TC4合金表面成功制备出TiN增强Ti基复合涂层。采用扫描电镜、X射线衍射仪分析了熔覆涂层的显微组织和物相组成;利用显微硬度仪、摩擦磨损试验机测试了复合涂层的显微硬度和室温干滑动磨损条件下的耐磨性能。结果表明:氩弧熔覆涂层组织均匀致密,熔覆层与基体呈冶金结合,熔覆涂层主要由TiN棒状树枝晶和TiN颗粒组成,复合涂层明显改善了TC4合金的表面硬度,涂层的最高显微硬度可达9.5 GPa;复合涂层在室温干滑动磨损实验条件下具有优异的耐磨性,磨损机制主要是磨粒磨损,其耐磨性较TC4合金基体提高近9倍。     

Ti和Nb对18Cr-2Mo铁素体不锈钢韧脆转变温度的影响

通过真空冶炼、锻造、热轧和退火试验制备出18Cr-2Mo铁素体不锈钢,结合其冲击试验和透射电子显微镜、扫描电子显微镜及电子背散射衍射等分析结果探讨了Ti和Nb微合金化对其韧脆转变温度的影响.结果表明：在C和N含量较低的条件下,添加微量元素Ti和Nb可以显著降低18Cr 2Mo铁素体不锈钢的韧脆转变温度（降低约40 °C）,并改变热轧后的织构类型而形成(001)和(111)复合织构;通过合适的退火工艺处理,可进一步提高其冲击韧性;在热轧过程中,产生细小弥散的Ti（N, C）和Nb（C, N）相是复合织构形成的主要原因.     

Grain refinement in the coarse-grained region of the heat-affected zone in low-carbon high-strength microalloyed steels

The microstructural features and grain refinement in the coarse-grained region of the heat-affected zone in low-carbon high-strength microalloyed steels were investigated using optical microscopy, scanning electron microscopy, and electron backscattering diffraction. The coarse-grained region of the heat-affected zone consists of predominantly bainite and a small proportion of acicular ferrite. Bainite packets are separated by high angle boundaries. Acicular ferrite laths or plates in the coarse-grained region of the heat-affected zone formed prior to bainite packets partition austenite grains into many smaller and separate areas, resulting in fine-grained mixed microstructures. Electron backscattering diffraction analysis indicates that the average crystallographic grain size of the coarse-grained region of the heat-affected zone reaches 6–9 μm, much smaller than that of austenite grains.     

搅拌方式对Ni-TiN复合镀层影响的研究

采用机械搅拌和超声波搅拌的电镀方法,在45钢基体上制备Ni-TiN复合镀层。利用原子吸收分光光度计(AAS)、扫描电镜(SEM)及摩擦磨损试验机对复合镀层的TiN粒子复合量、显微组织及其耐磨性能进行研究。结果表明,超声波搅拌-电沉积制备的Ni-TiN复合镀层,其TiN微粒的复合量最大值为10.7wt%,而机械搅拌-电沉积制得的Ni-TiN复合镀层,其TiN微粒的复合量最大值为8.8wt%。采用机械搅拌时,Ni-TiN复合镀层表面有大量粒径较大的颗粒出现,其平均粒径在3μm;而采用超声波搅拌时,Ni-TiN复合镀层表面颗粒相对较小,约为1μm。摩擦磨损试验表明,超声波搅拌-电沉积Ni-TiN复合镀层的磨损程度较小,而机械搅拌-电沉积Ni-TiN复合镀层的磨损程度则较为严重。     

基体梯度结构对TiN涂层硬质合金抗氧化性能的影响

采用阴极弧蒸发涂层工艺在均质和梯度硬质合金基体上沉积TiN涂层;运用金相观察、XRD检测和SEM分析,研究基体梯度结构对TiN涂层硬质合金抗氧化性能的影响,对涂层硬质合金氧化开裂过程进行分析。研究结果表明:基体结构梯度化后,TiN涂层的表面形貌由平整状变为网状结构;梯度基体表面韧性区的存在提高了TiN涂层硬质合金的抗氧化性能;在800℃氧化2 h后,2种涂层硬质合金边缘开裂,生成大量的氧化物;梯度基体涂层硬质合金开裂程度比均质基体涂层硬质合金的小。     

Effect of continuous annealing temperature on microstructure and properties of ferritic rolled interstitial-free steel

In this report, the microstructure, mechanical properties, and textures of warm rolled interstitial-free steel annealed at four different temperatures (730, 760, 790, and 820℃) were studied. The overall structural features of specimens were investigated by optical microscopy, and the textures were measured by X-ray diffraction (XRD). Nano-sized precipitates were then observed by a transmission electron microscope (TEM) on carbon extraction replicas. According to the results, with increased annealing temperatures, the ferrite grains grew; in addition, the sizes of Ti₄C₂S₂ and TiC precipitates also increased. Additionally, the sizes of TiN and TiS precipitates slightly changed. When the annealing temperature increased from 730 to 820℃, the yield strength (YS) and the ultimate tensile strength (UTS) showed a decreasing trend. Meanwhile, elongation and the strain harden exponent (n value) increased to 49.6% and 0.34, respectively. By comparing textures annealed at different temperatures, the intensity of {111} texture annealed at 820℃ was the largest, while the difference between the intensity of {111}<110> and {111}<112> was the smallest when the annealing temperature was 820℃. Therefore, the plastic strain ratio (r value) annealed at 820℃ was the highest.     

Synthesis of Mg2B2O5 whiskers via coprecipitation and sintering process

Mg₂B₂O₅ whiskers with high aspect ratio were synthesized by coprecipitation and sintering process using MgCl₂·6H₂O, H₃BO₃, and NaOH as raw materials and KCl as a flux. Their formation process was investigated by thermogravimetry and differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD), and scanning electron microcopy (SEM). It is found that the products synthesized at 832°C are monoclinic Mg₂B₂O₅ whiskers with a diameter of 200?C400 nm and a length of 50?C80 ??m. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) analyses show that the whiskers obtained at 832°C are single crystalline and grow along with the [010] direction. The growth mechanism of Mg₂B₂O₅ whiskers was also presented.     

A study of interparticulate strain in a hot-extruded SiC_p/2014 Al composite

We report a correlative study of strain distribution and grain structure in the Al matrix of a hot-extruded SiC particulate-reinforced Al composite(SiC_p/2014 Al). Finite element method(FEM) simulation and microstructure characterization indicate that the grain structure of the Al matrix is affected by the interparticulate strain distribution in the matrix during the process. Both electron-backscattered diffraction(EBSD) and selected-area electron diffraction(SAED) indicated localized misorientation in the Al matrix after hot extrusion. Scanning transmission electron microscopy(STEM) revealed fine and recrystallized grains adjacent to the Si C particulate and elongated grains between the particulates. This result is explained in terms of recrystallization under an interparticulate strain distribution during the hot extrusion process.     

Inhomogeneous deformation and recrystallization behavior of through-thickness tantalum sheet under one-cycle clock-rolling

Effects of low clock rolling passes on through-thickness deformation and recrystallization behavior of the Ta sheet have been investigated. The clock-rolled samples with one cycle (8 passes) were systematically examined under different thickness layers. X-ray diffraction (XRD) and X-ray diffraction line profile analysis (XLPA) showed that the extremely inhomogeneous texture evolution generated and the bulk stored energy existed in the through-thickness clock-rolled Ta sheet after 8 passes. The electron backscatter diffraction (EBSD) results revealed the misorientation of the grains in the deformed samples, indicating that grain subdivision in the surface and center layer was more serious than that in the quarter layer. High intensities misorientation indicates the presence of microshear bands in the surface and center layer. During annealing, the difference of the stored energy and the fragmentation of deformation microstructure along the thickness led to a heterogeneous driving force for the nucleation of the grains, resulting in subsequent different recrystallization rate in the different regions of the sample.     

原位观察TiN粒子对低合金高强度钢模拟焊接热影响区粗晶区晶粒细化作用

采用高温激光共聚焦显微镜原位观察和电子背散射衍射技术研究TiN粒子在低合金高强度钢模拟大线能量焊接热循环过程中晶粒细化效果。研究发现合理的Ti和N含量能形成大量细小弥散分布的纳米级TiN粒子,在焊接热循环过程中有效钉扎热影响区粗晶区奥氏体晶界,抑制晶粒粗化。同时,TiN附着在Al2 O3表面析出,在冷却过程中有效促进针状铁素体形核,得到有效晶粒尺寸非常细小的由少量针状铁素体和大量贝氏体构成的复合组织。     

氧化锌分级纳米结构的控制合成及光致发光性能研究(英文)

通过改变前驱物碱式碳酸锌的结晶度、尺寸和形貌,控制合成了分别由剑状晶须和纳米片自组装而成的多角星星形和花形氧化锌分级纳米结构。运用X-射线衍射和场发射电镜两种技术手段对所得产物进行了表征,并研究了产物的光致发光性能。在氧化锌分级纳米结构的形成过程中,前驱物碱式碳酸锌起到了重要的作用。     

Ni(OH)_2/USY分子筛复合材料的制备及其超级电容性能

以USY分子筛为模板,用液相共沉淀方法合成出Ni(OH)2/USY复合材料.用XRD、TEM对Ni(OH)2/USY复合材料的微观结构进行表征分析.结果表明,纳米级高分散、疏松填充的Ni(OH)2材料具有良好的电解质OH-离子电化学可及性和快的扩散速率,循环伏安和恒流充放电测试均表明该材料具有良好的超级电容特性,该材料的单电极比电容高达1 670 F/g.     

上转换材料复合介孔TiO2晶须的可见光催化性能

用溶胶凝胶法制备上转换发光材料Y3Al5O12:Er。反射光谱、发射光谱表明:Y3Al5O12:Er在480 nm光的激发下,产生2个<387 nm的紫外光发射峰。将上转换材料介孔TiO2晶须复合成可见光催化剂,采用X线衍射仪(XRD)、场发射扫描电子显微镜(FESEM)以及低温N2吸附-脱附(BET)等对催化剂进行表征,通过光催化降解亚甲基蓝(MB),对催化剂的活性进行测试。结果表明:复合上转换材料的介孔TiO2晶须在可见光下能够有效降解MB,10%Y3Al5O12:Er的介孔TiO2晶须的MB降解率为73%。     

螺旋形纳米碳晶须的结构及力学性能

用透射电镜(TEM)观察螺旋形碳晶须的微观形貌,并作选区电子衍射,分析其结构,可知螺旋形碳晶须的结构为六方晶体．由衍射图的圆弧可知,晶体为有结构的石墨多晶．将衍射图与形貌图对应起来,可知C轴与螺旋轴大致平行．将碳晶须放在压片机上加压,碳晶须在30MPa压强下受压15min后,无被损害之现象．     

自支撑GN/MnO2复合材料的制备及其 电容性能研究

本文通过水热辅助真空冻干法制备得到了可以自支撑的石墨烯/二氧化锰(GN/MnO_2)复合材料,利用X射线衍射仪(XRD)和扫描电子显微镜(SEM)分别对复合材料结构与形貌进行表征,并以复合材料为工作电极,组装成对称电容器,探究反应物质量比与电解液对材料电化学性能的影响,结果表明:在KOH电解液中,复合材料的比电容最大;当反应物质量比为1∶4时,该复合材料比电容可以达到224F/g(电流密度为1A/g).     

K2Ti6O13晶须增强角蛋白膜的力学性能表征

以六钛酸钾(K2Ti6O13)晶须作为增强体,制备了不同晶须质量分数和分散程度下的复合膜,并采用扫描电子显微镜(SEM)、强力仪和有限元分析(FEA)软件对复合膜的结构与性能进行考察.SEM观察结果表明,裂纹启裂于晶须头端与基体的界面处,可将复合膜断裂特征归纳为桥式短纤维破坏模型.力学试验结果表明,在晶须质量分数为3%且晶须分散均匀时,复合膜的综合力学性能最佳.对建立的二维细观结构有限元模型进行分析发现,有限元方法能够较好地解释微米晶须增强机理和复合膜失效机制.     

TiN/SiC纳米多层膜中的晶体互促生长

研究了TiN／SiC纳米多层膜中的晶体互促生长效应,采用磁控溅射法制备了一系列不同厚度SiC和TiN的TiN／SiC纳米多层膜以及TiN、SiC单层膜．利用透射电子显微镜、X射线衍射仪、扫描电子显微镜和X射线能量色散谱仪分析了多层膜的微结构．结果表明,尽管TiN和SiC的单层膜分别以纳米晶态和非晶态存在,但由TiN和SiC通过交替沉积形成的纳米多层膜却能够生长成为晶体完整性良好的柱状晶并呈现强烈的择优取向,显示了一种异质材料晶体生长的相互促进作用．纳米多层膜中的晶体互促生长效应与新沉积层原子在先沉积层表面上的移动性有重要关系。     

Effects of PSMA and experimental conditions on the morphologies of BaCO_3 whiskers

Effects of PSMA and experimental conditions on the morphologies of BaCO_3 whiskers     

激光熔覆Ni基涂层的稀释区与熔覆区界面形态及组织

在Ti6Al4V合金表面进行了激光重熔NiCrBSi/TiN，NiCrBSi/TiC喷涂层实验，利用扫描电镜和X射线衍射仪等手段对稀释区与熔覆区界面进行了观察。结果表明：NiCrBSi／TiC重熔层的稀释区与熔覆区界面平直，而NiCrBSi／TiN重熔层的稀释区与熔覆区的界面不复存在，是共晶组织和颗粒组织的混合区。分析认为，[C]、[N]活性原子在高温流动熔体内的不同行为，强烈地影响稀释区与熔覆区的界面性质。NiCrBSi／TiC、NiCrBSi／TiN激光重熔层中稀释区与熔覆区界面TiC和TiN相的形成，遵循化学反应的基本规律，即电负性原则。