渗碳淬火件取消回火的研究

0前言 　　一般零件在淬火后必须进行回火处理,以获得必要的强韧性配合.多年来,回火已成为渗碳淬火件的一个组成部分,为了保证耐磨性,多数的渗碳淬火件是在150℃～220℃的温度范围内回火,然而,这种低温回火的实际效果却成为一个有争议的问题.在优先考虑节约能源的今天,许多渗碳淬火件不经过回火已安装使用,可获得较高的疲劳强度.笔者经过多年调研工作,对渗碳淬火件取消回火工艺的可能性进行了一些初步研究,现分述如下. 　　……     

20Cr钢渗碳活塞销淬火后取消回火的试验

对２０Ｃｒ钢渗碳活塞销淬火后取消回火的原理进行阐述，并通过升项对比试验，得出取消回火能提高产品质量，延长零件使用寿命的结论，同时论证了取消回火工艺的可行性和优越性。     

18CrNi8针阀体真空脉冲渗碳热处理

本文着重对针阀体的材料选择,热处理工艺进行了分析和实践。证明采用真空脉冲式渗碳-正火-再加热马氏体等温淬火-冷处理-回火等热处理工艺,能有效地控制热处理变形,获得各处相同的渗碳层深度,优良的金相组织,良好的冷加工性能和零件的使用寿命。     

18CrNi8针阀体真空脉冲渗碳的热处理

本文徉重对针阀体的材料选择,热处理工艺进行了分析和实践。证明采用真空脉冲式渗碳——正火——再加热马氏体等温淬火——冷处理——回火等热处理工艺,能有效地控制热处理变形,获得各处相同的渗碳层深度,优良的金相组织,良好的冷加工性能和零件的使用寿命。     

连续装炉渗碳 实现节能

连续装炉渗碳　实现节能长庆石油勘探局机械厂刘永恒长庆石油学校王鹤１前言抽油泵是我厂的主导产品之一。缸套是抽油泵的关键零件，年生产数量很大，工艺要求渗碳、淬火并低温回火，以提高表面硬度、耐磨性和抗疲劳能力。我厂缸套渗碳所用设备为已改造的ＲＪＪ－１０５－...     

高压燃油喷射系统典型零件热处理工艺研究

主要研究了高压燃油喷射系统中典型深长孔结构零件的热处理工艺,研究了零件在炉内的布局方式,对比分析了多用炉渗碳、真空渗碳—真空淬火—高温回火渗碳、真空渗碳3种渗碳方式的碳层深度、金相组织以及3种渗碳方式真空油淬后的差异,筛选出最适合高压燃油喷射系统中典型深长孔结构零件的热处理工艺方案,并验证了该工艺方案的可靠稳定性。     

渗碳淬火的节能工艺

渗碳淬火的节能工艺管鄂（武汉水利电力大学，武汉，４３００７２）渗碳淬火是齿轮及其它需要表面强硬化工件常用的一种工艺。常规渗碳淬火有固体诊碳淬火及气体渗碳淬火两类。固体渗碳在９２０Ｃ以上高温区要维持８～１６ｈ以上，气体渗碳时间短一些，也在６～８ｈ以上，...     

氮气应用热处理技术(2)

文章围绕氮基气氛渗碳,介绍了气体量/组分可变式氮基气氛渗碳工艺的特点、气氛控制与氮基气氛渗碳材料的特性。对氮基气氛油回火工艺与实用化问     

SA-537MCl.2淬火加回火钢板埋弧自动焊焊接工艺

介绍SA-537MCl.2淬火加回火钢板埋弧自动焊焊接工艺,对焊接接头的力学性能进行了试验,并对性能试验结果作了简单的讨论。根据试验结果认为SA-537MCl.2淬火加回火钢板选用合适的焊接材料,采用埋弧自动焊可获得各项性能合格的焊接接头。     

渗碳淬火的节能工艺

文章分析了影响渗碳淬火能耗因素，提出了一种渗碳淬火节能工艺，结合实例，介绍了该节能工艺在齿轮箱厂的应用情况。     

Evaluation of in-situ formed La2O3–TiO2–La2O2CO3 nanocomposite photocatalyst for H2 production

The photocatalytic evolution of H₂ over La₂O₃ decorated TiO₂ catalyst was examined under solar light. It was observed that during the course of the reaction, the transformation of La₂O₃/TiO₂ into La₂O₃–TiO₂–La₂O₂CO₃ occurred and these species effectively suppressed electron-hole pair recombination by forming electron trapping centres on the surface, resulting in an increased visible light absorption and improved H₂ yield. The 2 wt%La₂O₃/TiO₂ nanocomposite demonstrated better H₂ yield (～8.76 mmol (g_cat)^?1) than the bare TiO₂ (～1.1 mmol (g_cat)^?1). The catalyst was stable even after several consecutive recycles with no substantial loss of hydrogen production rate. The H₂ rates were correlated with the physicochemical characteristics of the catalysts examined by BET–SA, H₂-TPR, XRD, UV-DRS, Raman spectroscopy, FTIR, HRTEM, EPR and PL spectroscopy.     

Photocatalytic H2 production over RuO2@ZnS and RuO2@CuS nanostructures

Photocatalytic hydrogen production is a promising approach of sustainable economy, because a use of sunlight and water to produce a fuel will solve a problem of fossil fuels depletion. Metal sulfides are well known photocatalysts in water splitting process, but in absence of sacrificial electron donor they undergo a photocorrosion. In this paper we studied a possible strategy to protect the sulfide photocatalysts and to improve its photostability by a deposition of small amount of ruthenium oxide at surface of sulfides. Nanocrystalline zinc sulfide and copper sulfide were prepared in a hydrothermal way and have been functionalized by RuO₂. As prepared photocatalysts showed good activity towards hydrogen formation. Modification of sulfides with ruthenium oxide had a few positive effects: it expanded a light absorption range by photocatalysts, enhanced the photocatalytic activity towards H₂ formation, improved a photostability in comparison with neat ZnS and CuS as well as protected from the electronic and structural changes within semiconductors due to irradiation.     

Numerical study of the O2/CO2, O2/CO2/N2, and O2/N2-syngas MILD combustion: Effects of oxidant temperature,O2 mole fraction,and fuel blends

Moderate or Intense Low-oxygen Dilution (MILD) combustion of a syngas fuel under air-fuel, oxygen-enhanced, and oxy-fuel condition are numerically studied with using counterflow diffusion flame. Fuel composition, temperature of oxidant (T_ox), and oxygen mole fraction (X_O2) are selected as the main parameters. Fake species (FCO₂) with the same CO₂ physical properties is used for separation the physical and chemical effects of replacing CO₂ with N₂. According to the results, under the high preheating temperatures, the chemical effect of changing the oxidant composition from N₂ to CO₂ is the main reason of the changes in flame structure, ignition delay time (IDT) and heat release rate (HRR) while physical differences play a more prominent role in the low preheating temperature MILD combustion. In all X_O2, the physical and chemical effects of replacing CO₂ with N₂ have almost the same role on the maximum flame temperature. The results of IDT expressed that chemical discrepancies of CO₂ and N₂ play a key role on IDT enhancement by increasing CO₂ in the oxidant composition. The sensitivity analysis of CH₂O for variations of T_ox and X_O2 shows that reactions R54, R56, R58, and R101 are the main responsible of lower HRR and higher IDT by moving from air-syngas to oxy-fuel MILD combustion.     

Photocatalytic reduction of CO2 using TiO2 powders in supercritical fluid CO2

The photocatalytic reduction of CO₂ was investigated using TiO₂ powders in supercritical fluid CO₂. These were irradiated in a stainless steel vessel at 9.0 MPa and 35°C. After reducing the CO₂ pressure to the ordinary state, pure water was added to the vessel while avoiding air contamination. No gaseous reduction products were observed. Formic acid was obtained only in aqueous solution. The optimal irradiation time for the production of formic acid was 5 h. Addition of acidic solutions rather than pure water was preferable for formic acid formation. Formic acid seems to be produced through the protonation of reaction intermediates on TiO₂ powders in solutions. The CO₂-reduction system described here may be of practical value for efficient CO₂-conversion and fixation, storage of solar energy, and production of raw materials for the photochemical industry.     

保护气氛烧结炉

介绍了HIC封装管壳中玻璃绝缘子网带烧结炉的特殊机械结构、氮氢保护气氛系统和电气保护措施。确立了网带炉低速爬行力学模型及炉内合理的气氛流向。     

New gas chromatographic packing ZIF-67@NH2–SiO2 for separation of hydrogen isotope H2/D2

ZIF-67@NH₂–SiO₂ composites were prepared by loading the metal-organic frameworks ZIF-67 on amino modified SiO₂ gel particles (NH₂–SiO₂, 80–100 mesh) through layer-by-layer self-assembly method. Systematic investigation on the effects of ZIF-67 loading amounts on NH₂–SiO₂ packed stainless steel chromatographic column (specification 1.0 m×2.0 mm I.D.), the flow rate of He as carrier gas and the injection amount of mixed gas (H₂/D₂) on the hydrogen isotope H₂/D₂ separation performance at liquid nitrogen temperature, unraveled the optimal conditions for H₂/D₂ isotope separation. The results showed that the optimal stationary phase materials under the optimized conditions can effectively separate H₂ and D₂ with separation resolution R = 1.52 and the separation time t = 10.15 min. The superior performance of the ZIF-67 is tentatively thought to be due to kinetic quantum sieving (pore size 3.3 Å) effect and chemical affinity sieving effect of Co ion in ZIF-67.     

Photocatalytic reduction of CO2 with H2O on CuO/TiO2 catalysts

Carbon dioxide was photocatalytically reduced to produce methanol and ethanol in the presence of CuO-loaded titania powders suspended in water containing Na₂SO₃ as the hole scavenger. The photocatalysts were synthesized by an impregnation method using P25 (Degussa) as support. At the optimum amount of copper oxide loading (3 wt%), the methanol and ethanol yields were 12.5 and 27.1 μmol/g-catal., respectively, following 6 h of UV illumination. The redistribution of photogenerated charge carriers in CuO/TiO₂ facilitates electron trapping and prohibits the recombination of electrons and holes, which significantly increases photoefficiency. The addition of Na₂SO₃ promotes the formation of ethanol.     

固体超强酸SO2-4/TiO2-SiO2催化制备生物柴油

叙述了以固体超强酸SO4^2-／TiO2-SiO2为催化剂,催化大豆油和甲醇的酯交换反应制备生物柴油的实验。结果表明,该催化剂对酯交换反应有很高的催化活性,催化剂的活性不受体系中游离脂肪酸的影响。在醇油摩尔比为13：1时,每摩尔油使用1．0g催化剂,125℃反应3h,脂肪酸甲酯的收率达90％。催化剂的吡啶红外谱图表明催化剂具有L酸中心和B酸中心,催化剂的NH3-TPD曲线表明催化剂具有超强酸性。