新型塑料模具钢4Cr2Mn2NiMoV的研制

新研制的塑料模具钢为 4Cr2Mn2NiMoV ,经金相分析和力学性能检验及厂家使用表明 ,其特点是淬透性及抛光性能良好 ,预硬处理后经机械加工即可直接使用 ,是一种值得推广的新钢种。     

New C–Si–Mn–Cr–V–Mo powder wires for roller surfacing

Laboratory data indicate the positive effects of introducing fluorocarbon and nickel in 25Kh5FMS steel powder wire for the surfacing of rollers. In particular, the replacement of amorphous carbon by a material containing fluorocarbon lowers the content of nonmetallic inclusions in the applied layer, while introducing nickel in the powder wire reduces the austenite grain size and ensures the formation of small carbide particles. That increases the thermal stability of the applied layer. Increase in the carbon equivalent of the 25Kh5FMS powder wire boosts the hardness of the applied metal layer.     

Hydrometallurgical Processing Routes in the Synthesis of Advanced Materials

Abstract

Hydrometallurgical processing routes show outstanding potential for synthesizing a wide range of advanced ceramic and metallic materials, in which the composition, purity and structure are closely controlled to produce- materials with the properties needed for specific applications. The characteristics of "advanced materials'* are first discussed in general terms. Those classes of materials most likely to be amenable to hydrometallurgical processing are then considered, and the economic, technical and environmental benefits that might be derived from adopting hydrometallurgical processing routes are discussed. The thermodynamic, surface chemical, kinetic, and transport principles that could be used to control the materials characteristics are then reviewed. Finally, selected examples of aqueous processing techniques for preparing both oxide ceramics and metallic materials, as powders, films or coatings, are provided.     

Synthesis of LiSm0.01Mn1.99O4 by molten salt technique

Samarium substituted lithium manganese oxide powders were successfully prepared by molten-salt synthesis(MSS) using eutectic mixture of LiCl,SmCl3.6H2O and MnO2 salt at 700 °C.The synthesis was carried out in open atmosphere.The crystalline powders were characterized for their phase identification using X-ray diffraction(XRD) analysis.The physico-chemical properties of the samarium substituted lithium manganese oxide powders were investigated by thermal analysis(TGA/DTA),FT-IR spectroscopy,EDAX,electron par...     

Acid dissolution of willemite (Zn,Mn)2 SiO4) and hemimorphite (Zn4Si2O7(OH)2 H2O)

The influence of temperature, pH, acid type, and surface area on the kinetics of the acid dissolution of natural and synthetic willemites and natural hemimorphites has been investigated. Specific rate constants, based upon areas determined by krypton adsorption measurements, were estimated from the experimental data obtained. For both willemite and hemimorphite, the rates of dissolution in different acids are shown to be related to the relative strengths of zinc-acid anion complexes. The reactivity of willemite toward acids increases with increasing replacement of zinc by manganese. Mixed chemical/diffusion control is responsible for the observed rates of willemite dissolution under the conditions studied (HNO₃, HCl, HClO₄, H₃PO₄, H₂SO₄, pH 0.31 to 3.00,T 21 to 94 °C). Estimates of the relative contributions of chemical and diffusional resistances to the overall rate have been made for the dissolution of manganese-free willemite in sulfuric acid solutions. The experimentally measured rates have been demonstrated to be in reasonable agreement with predicted overall dissolution rates. Proposals are made regarding the nature of the diffusion and chemical steps involved in the dissolution process. Hemimorphite was found to be considerably more reactive than willemite and its dissolution is primarily diffusion controlled under the conditions studied (T 20 to 76 °C, pH 2 to 3.5). Formerly a Postgraduate Research Student, Department of Metallurgy and Materials Science, Royal School of Mines, Imperial College, London     

60Si2Mn面缩率降低成因研究

基于对弹簧钢面缩率不合格炉次的工艺条件和低倍试样数据统计，对连铸弹簧钢面缩率降低的影响因素进行了分析，认为其主要原因是铸坯中心碳偏析、夹杂等低倍缺陷所致，而且注意到钢中的氢亦是影响面缩率的重要原因，并根据目前装备情况提出了整改措施，使大规格弹簧面缩合格率达到85％以上。     

熔融法在X荧光分析硅锰合金中的应用

对硅锰合金前期氧化处理的方法进行研究，氧化后的硅锰合金方可安全使用铂金坩埚熔融、制得均勾硅锰合金玻璃融片、消除了Ｘ荧光分析中因硅锰合金的粒度和基体的吸收增强效应对分析结果约影响，分析结构令人满意。     

PC钢棒用30Si2Mn盘条的试制

文章叙述了包钢采用150 mm×150 mm连铸坯生产PC钢棒用30Si2Mn盘条的试制过程,给出了试验结果。结果表明,采用小方坯工艺开发的30Si2Mn PC制品用盘条是成功的,各项指标均满足用户要求。     

Investigation on the Effect of ECAP Routes on the Wear Behavior of AA2014

ECAP is an effective process to improve the mechanical strength and wear resistance along with mechanical and microstructural properties. AA2014 solutionized at 495 °C and aged at 195 °C was subjected to Equal Channel Angular Pressed (ECAP) through route A and B_c at room temperature. It was well proved that the mechanical strength increased due to ECAP in AA2014. In order to investigate their wear behavior after ECAP, dry sliding wear tests were conducted using vacuum tribometer at nominal loads of 10N and 30N with constant speed of 2 m/s for sliding distance of 2000 m. The co-efficient of friction and loss in volume were decreased after ECAP both in route A and B_c. The dominant wear mechanisms observed were adhesive, delamination and stick slip process. In addition to these wear mechanisms, abrasive wear also appeared along with transfer of iron particles from the counter surface to the AA2014 pin. Presence of black powder and oxide formation were observed using EDAX analysis on wear debris. Routes A and B_c showed similar wear mechanisms and characteristics which were better than in unECAPed specimens.     

X射线荧光光谱法测定硅、磷、铬、锰、铁

以[ KNO3+NaNO3+Sr( NO3)2]为氧化剂,Na2CO3为助熔剂,Li2B4O7作熔剂,采用熔片法制备样片,建立了高碳铬铁、碳素铬铁、炉料级铬铁中硅、磷、铬、锰、铁的X射线荧光光谱分析方法,本方法采用国家标准样品和分析试样绘制了工作曲线,进行了精密度和准确度试验,其测定值与标准值相符,并有良好的精密度,完...     

60Si2Mn冶炼工艺技术分析

分析了６０Ｓｉ２Ｍｎ的冶炬工艺技术情况，对其存在的问题提出改进措施。     

Thermodynamic Properties of Si - Mn - Y System Alloys

High-temperature isoperibolic calorimetry has been used to measure the partial enthalpies of mixing for yttrium in the Si - Mn - Y ternary system at 1775 K along sections with various atomic ratios of silicon to manganese (0.85/0.15; 0.7/0.3; 0.6/0.4; 0.5/0.5; 0.3/0.7) for yttrium concentrations in the range 0 < x_Y < 0.4 together with the partial molar enthalpies of manganese for x_Si/x_Y = 0.8/0.2. The integral enthalpies of mixing have been calculated from the partial ones for yttrium by Darken’s method. The addition of yttrium to the Si - M binary system to give the ternary Si - Mn - Y system increases the exothermic effects of the alloying substantially. There is a substantial effect on the thermodynamic parameters of the ternary alloys from the atomic interactions in the Si - Y and Si - Mn binary systems.__________Translated from Poroshkovaya Metallurgiya, Nos. 3–4(442), pp. 64–69, March–April, 2005.     

60Si2Mn连铸方坯的生产实践

石横特钢厂通过严格保证钢水质量，控制钢水及铸坯温度，拉坯速度和冷却强度，并采用浸入式水口保持浇注技术，在普通机上生产出合格的优质钢连铸坯，文章以６０Ｓｉ２Ｍｎ合金弹簧钢为重点，阐述了生产符合标准要求的优质钢连铸方坯的电炉冶金及Ｒ５．２５ｍ罗可普型小方坯铸机的生产工艺参数。