磁控反应溅射MoS2/Ti/C复合薄膜的组织结构及摩擦磨损性能

为了提高MoS2薄膜在室温潮湿大气条件下的摩擦磨损性能,通过磁控反应溅射制备了MoS2/Ti/C复合薄膜.采用能谱仪(EDS)、X射线衍射仪(XRD)、场发射扫描电子显微镜(FESEM)对薄膜的成分、相组成和形貌进行表征,采用纳米压痕仪测试薄膜的结合力、纳米压痕硬度,采用多功能微摩擦磨损试验机测试薄膜的摩擦系数,并采用...     

脉冲激光沉积VN/Ag复合薄膜的组织及摩擦学性能研究

利用脉冲激光沉积技术制备了不同Ag含量的VN/Ag复合薄膜,利用扫描电子显微镜、X射线衍射仪、纳米力学测试系统等设备表征薄膜的组织结构、成分、表面形貌及力学性能,利用UMT-3摩擦试验机考察薄膜在室温至900℃下的摩擦学性能。结果表明,随着Ag含量的增多,薄膜的组织形貌变差,硬度及弹性模量降低。当Ag含量为16%(原子分数)时薄膜在试验温度范围内的摩擦学性能最佳。由于Ag在低温的润滑特性及高温摩擦化学反应生成了新的润滑相,如V2O5、V6O11、V6O13、Ag3VO4、AgVO3等,使得摩擦系数随温度的升高而逐渐降低,在900℃下取得最低值0.08,实现了宽温域内的连续润滑。     

CrTiAlN薄膜的微观结构及其高温摩擦磨损性能

采用闭合场非平衡磁控溅射离子镀技术,在M2高速钢表面制备CrTiAlN多层薄膜。利用XRD、SEM、EDS和球-盘式摩擦磨损试验机研究薄膜微观结构和高温摩擦磨损性能。结果表明:CrTiAlN薄膜均匀致密,呈FCC结构。高温摩擦磨损试验表明:从室温到600℃,随着温度升高,薄膜摩擦系数先增大后减小,磨损量和磨损率随着温度升高而增加,CrTiAlN薄膜在600℃环境下的磨损形式主要是氧化磨损和磨粒磨损。     

脉冲激光沉积VN/Ag复合薄膜的组织及摩擦学性能研究

利用脉冲激光沉积技术制备了不同Ag含量的VN/Ag复合薄膜,利用扫描电子显微镜、X射线衍射仪、纳米力学测试系统等设备袁征薄膜的组织结构、成分、表面形貌及力学性能,利用UMT-3摩擦试验机考察薄膜在室温至900℃下的摩擦学性能.结果表明,随着Ag含量的增多,薄膜的组织形貌变差,硬度及弹性模量降低.当Ag含量为16％(原子分数)时薄膜在试验温度范围内的摩擦学性能最佳.由于Ag在低温的润滑特性及高温摩擦化学反应生成了新的润滑相,如V2O5、V6O11、V6O13、Ag3VO4、AgVO3等,使得摩擦系数随温度的升高而逐渐降低,在900℃下取得最低值0.08,实现了宽温域内的连续润滑.     

Fe-Mo-(MoS2/PbO)高温自润滑材料的摩擦学特性

采用粉末冶金热压烧结工艺制备了一种在高温下具有良好摩擦学性能的Fe-Mo-(MoS2/PbO)自润滑材料,考察了其在室温和600℃下的摩擦磨损性能,并运用扫描电子显微镜(SEM)、X射线光电子能谱(XPS),X射线衍射(XRD)等分析手段揭示了Fe-Mo-(MoS2/PbO)高温自润滑材料的摩擦磨损机理.研究结果表明:由于摩擦和高温氧化作用,该类材料在600℃下磨损表面的复合润滑膜(由PbMoO4、Pb、Fe2O3和Fe3O4组成)是其具有良好自润滑性能的主要原因.     

真空烧结纳米La_2O_3掺杂MoSi_2复合涂层的高温摩擦学性能

采用高温真空烧结法在高速钢基体表面上制备了纳米氧化镧掺杂二硅化钼基复合涂层;考察了温度(200~800℃)、纳米La_2O_3含量(1%、3%和5%)(质量比)对MoSi_2基复合涂层高温摩擦学性能的影响规律;采用X射线衍射表征了MoSi_2基复合涂层高温摩擦磨损前后的微结构,探讨了复合涂层的高温摩擦磨损机理。研究结果表明纳米La_2O_3掺杂MoSi_2基复合材料摩擦学性能在低温(200℃)和高温(800℃)下纳米La_2O_3含量为3%时较好,摩擦系数为0.1。通过引入纳米La_2O_3可有效地改善Mo Si2的高温摩擦学性能,其磨损机理主要为磨粒磨损、粘着磨损和氧化磨损的复合磨损。     

磁控溅射MoS2/W复合薄膜的微结构与摩擦学性能研究

采用磁控溅射法,用纯MoS2/W双靶在模具钢Cr12和硅基片上溅射MoS2/W复合纳米薄膜,通过X射线衍射仪、能谱仪、扫描电子显微镜对薄膜的成分和结构进行分析.采用UMT-2型微摩擦磨损试验机在大气(相对湿度30％～ 45％)和室温(20～25℃)环境下评价薄膜的摩擦磨损性能.结果表明:MoS2/W复合薄膜组织致密,主要生长晶向为(002)晶向,摩擦因数低,摩擦学性能优于纯MoS2膜,且耐磨寿命高、摩擦稳定性好、承载能力大.     

环境和法向载荷对(TiVCrAlMo)N高熵合金薄膜摩擦学性能的影响

本工作研究了(TiVCrAlMo)N高熵合金薄膜在干摩擦、16烷、去离子水及三种粘度润滑油(0W-20、10W-30及5W-40)下的摩擦学行为,并探究了不同载荷(1 N、2 N和3 N)对其摩擦学性能的影响。结果表明：1 N和2 N下,高熵合金薄膜在16烷和润滑油中的摩擦系数远低于在干摩擦和去离子水中的摩擦系数,但在3 N下,高熵合金薄膜在去离子水中的摩擦系数出现大幅下降。在油润滑下,高熵合金薄膜在低粘度润滑油(0W-20)中的磨损率随载荷的增加而增大,而在中粘度润滑油(10W-30)中的磨损率随载荷的增加而减小,但在高粘度润滑油(5W-40)中的磨损率与载荷之间无明显的线性关系。高熵合金薄膜在干摩擦中的磨损机制是磨粒磨损和分层磨损,但随载荷的增加还伴有氧化磨损;在16烷中的磨损机制是疲劳磨损和氧化磨损,但在1 N下仅为轻微磨粒磨损;在去离子水中的磨损机制为磨粒磨损和氧化磨损。高熵合金薄膜在低粘度润滑油(0W-20)中1 N下的磨损机制是轻微磨粒磨损,但随载荷的增加转为疲劳磨损;相反的是,在中粘度润滑油(10W-30)中的磨损机制是疲劳磨损,但随载荷的增加转为轻微磨粒磨损;此外,高熵...     

固体润滑剂对芳纶纤维增强尼龙66材料摩擦学性能的影响

本文研究了PTFE和MoS2两种固体润滑剂对芳纶纤维(AF)增强尼龙66(PA66)复合材料摩擦磨损性能的影响,进行了摩擦学测试,利用扫描电镜对其磨损微观形貌进行分析.结果表明,PTFE有效改善了复合材料的摩擦学性能,降低了材料的摩擦系数,提高了耐磨性;MoS2的加入并未改善其摩擦学性能.XPS分析表明:MoS2在摩擦过程中发生摩擦化学反应,生成了MoO3,产生严重的磨粒磨损.     

高温热处理C/C对C/C配对C/C-SiC摩擦学性能的影响（英文）

采用化学气相渗透法(CVI)工艺制备C/C复合材料,然后在2 300℃处理其中一个C/C试样。通过化学气相渗透法结合液体硅渗透法(LSI)制备C/C-SiC复合材料。为了提高制动的稳定性并期望克服C/C和C/C-SiC自磨的缺点,在MM-3 000型摩擦磨损试验机上研究了C/C配对C/C-SiC摩擦副的摩擦学性能。结果表明,经2 300℃高温热处理(HTT)的C/C配对C/C-SiC的平均摩擦系数(COF)为0.280,稳定摩擦系数为0.65,而没有经过高温热处理的C/C配对C/C-SiC摩擦副的平均摩擦系数及稳定摩擦系数分别为0.451和0.55。经过2 300℃高温热处理和没经过高温热处理的C/C的线磨损率分别为8.9μm/(slide cycle)和3.7μm/(slide cycle)。由于高温热处理会引起碳软化,导致了经过2 300℃高温热处理的C/C磨损率增加。总之,经过高温热处理的C/C配对C/C-SiC在提高稳定摩擦系数的同时不能改善其他摩擦磨损性能。C/C配对C/C-SiC的磨损机理主要是磨粒磨损,氧化磨损和疲劳磨损。     

Measurement of solubility and density of water + lithium bromide + lithium chloride and water + lithium bromide + sodium formate systems

Solubility of aqueous solutions containing lithium bromide + lithium chloride and lithium bromide + sodium formate were measured (LiBr/NaHCO₂ = 2 and LiBr/LiCl = 2 by mass ratio) at different temperatures. Visual polythermal method was used in the temperature range of (283.15–340.15) K and mass fraction range of (0.4–0.8). Also density of mentioned systems was reported in the temperature range of (288.15–333.15) K. Each set of experimental measurements were correlated using least-square regression as a function of temperature. Our results indicate that solubility of LiBr + LiCl is higher than LiBr and its density is lower than density of aqueous solution of LiBr.     

H+ and He+ spectroscopy using silicon pin photodiodes

Silicon PIN photodiodes have been used in detecting H⁺ and He⁺ ions from a 1 MeV accelerator. Energy resolutions (FWHM) from 2.0 keV (at 16 keV) to 4.7 keV (at 1 MeV) for H⁺ and from 3.4 keV (at 22 keV) to 9.8 keV (at 700 keV) for He⁺ have been measured at room temperature. Resolution measurements over this energy range using a premium PIPS detector have also been performed. A comparison between the two detectors shows that the photodiodes exhibit better energy resolution over the whole energy range for H⁺, and comparable resolution for He⁺. It is argued that the resolution of the photodiode can be further improved by manufacturing a device with thinner entrance window.     

Electrical characterization of Si+ and Si+/P+ implanted N+P+In0.53Ga0.47As junctions

In this communication, we present I–V and admittance spectroscopy measurements of shallow n⁺p junctions into p-InGaAs made by Si⁺ implantation, including a complete study of the conduction mechanisms as a function of temperature. The effect of P⁺ co-implantation is also analysed. The I–V characteristics of both junctions show that recombination in the space-charge zone is the dominant transport mechanism in forward bias, with ideality factors around 1.5 at 300 K that increase with decreasing temperature of measurement. Activation energies of the reverse saturation current are obtained at room temperature, being 0.5 eV and 0.4 eV for Si⁺ and Si⁺P⁺ implanted diodes, respectively, indicating that recombination currents occur through a near midgap center. Reverse current–voltage measurements show a higher conduction in the P⁺ co-implanted junction due to a higher concentration of traps. In both types of junctions, the reverse characteristics can be fitted to a thermally-activated trap-assisted tunneling mechanism at low bias, involving traps at 0.41 eV and 0.44 eV for Si⁺ and P⁺ co-implanted junctions, respectively, whereas different trap-assisted tunneling processes dominate at medium and high bias. The small signal analysis show a clear difference between the two types of junctions. The use of Kramers–Kronig transforms on the admittance spectroscopy data reveals the presence of a defect level at 0.35 eV in both types of junctions, probably assigned to Zn, the native acceptor present in the p-InGaAs. Another trap level at 0.30 eV is detected at the P⁺ co-implanted junctions, not appearing in the Si doped junctions, which could probably be due to damage produced by the co-implantation.     

Phase transformations in Ni + Al and Ni + Al + Cr mixtures during mechanochemical synthesis and subsequent heating

Mechanochemical processing of elemental mixtures with the compositions Ni₇₅Al₂₅, Ni₇₀Al₂₅Cr₅, and Ni₇₅Al₂₀Cr₅ (5 at % Cr in the mixtures instead of the equivalent amount of Ni or Al) leads to the formation of nanocrystalline nickel-based solid solutions (crystallite size in the range ? 7?C12 nm). Comparison of experimentally determined lattice parameters of the solid solutions with Vegard??s law values and with the lattice parameters evaluated using the Bozzolo-Ferrante rule, which takes into account the bulk moduli of constituent elements, suggests that the atoms in the solid solutions are bonded more strongly. Heating the synthesized ternary solid solutions in a calorimeter to 1000°C leads to the formation of an ordered ?á?-phase (L1₂). Analysis of the relative intensity ratio of superlattice and fundamental reflections indicates that the Cr atoms always reside in the Al sublattice, independent of the composition of the starting mixture. When 5 at % Cr is incorporated instead of Ni, the chromium atoms force out aluminum from the Al sublattice, and the Ni deficiency in the Ni sublattice is compensated by the Al atoms. The ordered phases remain nanocrystalline (crystallite size in the range ? 40?C70 nm).     

La3+ and Ce3+ Doping of Hard-Magnetic Ferrites

Rare-earth-doped ferrites with the general formula M_{1 – x} R _x · nFe₂O₃ (M = Ba, Sr, Pb; R = La, Ce; x = 0–0.1; n = 4–6) are prepared by solid-state combustion synthesis. The effects of the doping procedure (before or after combustion synthesis), dopant content, and heat-treatment conditions on the magnetic and mechanical properties of the ferrites are examined. The results indicate that doped materials can be used to fabricate permanent magnets with enhanced density, remanence, and energy product. In addition, rare-earth doping improves the strength of the ferrite materials, eliminating their main drawback—inherent brittleness.     

Mechanochemical fabrication of C (matrix) + Cu + Si + W + Mo nanocomposites

Using magnesiothermic reduction of WO₃, MoO₃, SiO₂, and CuO through mechanochemical activation, we prepared high-purity (∼99.3%) nanopowders with a particle size from 9 to 350 nm for the fabrication of functional materials and nanocomposite systems for anode electrodes of lithium ion (polymeric) batteries.     

Solubilities, Vapor Pressures, and Heat Capacities of the Water + Lithium Bromide + Lithium Nitrate + Lithium Iodide + Lithium Chloride System

The optimum mole ratio of lithium salts in the H₂O + LiBr + LiNO₃ + LiI + LiCl system was experimentally determined to be LiBr : LiNO₃ : LiI : LiCl = 5 : 1 : 1 : 2. The solubilities were measured at temperatures from 252.02 to 336.75 K. Regression equations on the solubility data were obtained with a least-squares method. Average absolute deviations of the calculated values from the experimental data were 0.15% at temperatures <285.18 K and 0.05% at temperatures 285.18 K. The vapor pressures were measured at concentrations ranging from 50.0 to 70.0 mass% and at temperatures from 330.13 to 434.88 K. The experimental data were correlated with an Antoine-type equation, and the average absolute deviation of the calculated values from the experimental data was 2.25%. The heat capacities were measured at concentrations from 50.0 to 65.0 mass% and temperatures from 298.15 to 328.15 K. The average absolute deviation of the values calculated by the regression equation from the experimental data was 0.24%.