共查询到20条相似文献,搜索用时 62 毫秒
1.
采用离子氮化+双层辉光离子渗金属的复合处理渗铬新技术,对碳素工具钢进行560℃表面渗镀铬硬化研究。结果表明,渗镀层组织由沉积层+扩散层组成;渗镀层表面形成4~5μm的沉积层,含铬量达50%以上,致密并与基体冶金结合;内有20-25μm的扩散层,扩散层含铬量呈梯度分布;经X射线衍射分析,其表面物相由Fe-Cr、CrN、Cr7C3、Cr23C6等组成;渗镀层的显微硬度达1000HV以上,硬度向内逐步降低,呈梯度分布。 相似文献
2.
利用双层辉光等离子渗金属技术,在580℃对T10钢进行表面渗镀铬硬化的研究.结果表明:渗镀层由沉积层 扩散层组成;沉积层厚5~6μm,组织致密,与基体结合紧密,且w(Cr)>48%;内有15~20μm的扩散层,扩散层中铬含量呈梯度分布;经X射线衍射分析,其表面物相由Fe、Fe-Cr、Cr7C3、Cr23C6、等组成;渗层的显微硬度达700HV以上,硬度向内逐步降低,且呈梯度分布. 相似文献
3.
采用双辉等离子渗铬+离子渗氮的复合工艺,以T10钢为基材在560℃研究了该工艺对渗层硬化效果的影响。结果表明:离子渗氮前渗层表面有3-5μm的沉积层,组织致密并与基体结合紧密,基体组织无明显变化;沉积层含铬量达46%以上,扩散层深15-20μm;渗层表面物相均由Fe、Fe-Cr、Cr7C3、Cr23C6等组成;表面显微硬度达650-850HV,硬度向内呈梯度分布。渗镀层经离子渗氮后的组织与氮化前的组织无明显变化,但表面物相为Fe-Cr、Cr7C3、Cr23C6、CrN、Fe4N,表面显微硬度1000-1350HV,较未渗氮前提高65%以上,表明本复合工艺能有效提高铬渗镀层的显微硬度。 相似文献
4.
γ-TiAl合金表面辉光等离子渗Cr层的组织与性能 总被引:2,自引:1,他引:1
利用双层辉光等离子表面渗金属技术(DGPSAT)在γ-Tial合金表面进行等离子渗Cr处理,采用OM、SEM、EDS和XRD分析了渗Cr合金层的显微组织、化学成分及其相组成,并测试了其显微硬度分布和耐磨性.结果表明,γ-TiAl合金经双层辉光等离子渗Cr处理后,其表面形成以Al8Cr5、TiAl、Ti3Al、Cr等相组成的合金层,有效厚度约为35μm,渗层与基体结合牢固;渗Cr层组织成分及其横截面显微硬度由表及里均呈梯度分布;其摩擦磨损性能亦得到提高. 相似文献
5.
采用双层辉光等离子表面冶金技术在γ-TiAl合金表面进行Ni-Cr共渗处理,形成均匀致密的Ni-Cr合金层,通过SEM、EDS、XRD等对其渗层显微组织、化学成分和相结构进行分析,并测试了合金层的显微硬度及耐磨性。结果表明,合金层有效渗层厚度为25μm,主要由Cr2 Ti、AlTi、Cr、NiTi2、Cr1.75 Ni0.25 Ti等相组成;合金层中合金元素Cr和Ni由表及里呈梯度分布,合金层与基体结合牢固;合金层的显微硬度、动态硬度及摩擦磨损性能显著高于基体。 相似文献
6.
7.
在TC11钛合金表面等离子渗Mo以提高其耐磨性。利用SEM、EDS、XRD分析了渗Mo层的微观组织、化学成分及相组成,测定了渗层的硬度分布。采用划痕试验测定了渗层与基体的结合力。通过球盘磨损试验测定了等离子渗Mo层的摩擦磨损性能。结果表明,渗层厚度为30μm;0~10μm表层Mo含量为65%,由表及里呈梯度降低;渗层由单质Mo以及Al8Mo3和Al3Ti等化合物组成,表面硬度达1034 HV0.1;渗层与基体的结合力为70 N;渗层的比磨损率是基体的1/55.4。 相似文献
8.
9.
10.
11.
Deng-Kui Zhang Guo-Qing Wang Ai-Ping Wu Ji-Guo Shan Yue Zhao Tian-Yi Zhao Dan-Yang Meng Jian-Ling Song Zhong-Ping Zhang 《金属学报(英文版)》2019,32(6):684-694
In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone. 相似文献
12.
After nearly two years'tense construction the first phase of industrialized base of Shenyang Research Institute of Foundry 《中国铸造》2008,5(1):63-64
After nearly two years' tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry (SRIF), located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation. 相似文献
13.
Z. Sun S.L. Zheng Y. Zhang 《金属学报(英文版)》2007,20(3):187-192
Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process. 相似文献
14.
R. González-Martínez 《金属学报(英文版)》2007,20(4):235-240
The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke. 相似文献
15.
The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C). 相似文献
16.
The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel. 相似文献
17.
B.W. Zhang B.W. Li 《金属学报(英文版)》2007,20(2):129-138
On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes' collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process. 相似文献
18.
R.Z. Wu Z.K. Qu B.D. Sun D. Shu J. Wang 《金属学报(英文版)》2007,20(3):193-198
The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results. 相似文献
19.
This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before. 相似文献
20.
Chao Yang He-Fei Huang Massey de los Reyes Long Yan Xing-Tai Zhou Tian Xia De-Liang Zhang 《金属学报(英文版)》2015,28(7):809
Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties. 相似文献