高效节能环保渗碳渗氮技术

介绍了四个内容：（1）新型高效、节能、环保渗碳技术,主要包括预抽真空双室多用炉和气氛控制装置,与通常的气体渗碳相比,渗碳速度更快,内氧化、渗碳气体消耗量及 CO2排放量大大减少;（2）控制气氛真空渗碳炉,该炉采用热传导探头和氧探头双探头进行碳势的闭环控制,可实施真空渗碳、气冷、重新加热至850℃淬火的工艺过程,渗层均匀性好,并能有效消除积炭;（3）预抽真空精密控制气氛渗氮炉,该炉采用独特的温度和氮势精确控制系统,可取代QPQ 技术对普通碳钢进行渗氮氧化复合处理,提高其耐磨、耐蚀和疲劳性能;（4）活性屏等离子渗氮技术,其独特之处是,高压直流电源的负极接在真空室内的金属活性屏上,等离子体加热金属屏,由从屏上辐射的热量将工件加热到所需渗氮温度,解决了传统的直流等离子渗氮技术难以克服的工件打弧等问题。     

Effect of commercial carbon-containing controlled atmosphere composition on the intensity of article carburization

A reduction in the duration of carbon impregnation during gas carburizing is normally achieved either by increasing the temperature of the process or creating rapid circulation of the atmosphere within the furnace. Both of these methods have their specific drawbacks and it is difficult to accomplish them in practice. A simpler and cheaper method is carbon impregnation without controlled atmospheres containing only CO and H₂. Here alongside a reduction in the duration of the process it is possible to use slow atmosphere velocities within the charge which simplifies the construction of the carburizing furnace.Moscow Automobile Building Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 10, pp. 24–26, October, 1994.     

VKA-D真空渗氮回火多功能炉及其控制系统

VKA-D系列真空渗氮、回火多功能炉为马弗密闭结构,通过预抽真空实现全过程无氧化处理,从而提高工件的渗氮质量;采用内外双冷却系统,实现冷却速度可控,并提高生产效率.采用独特的控温装置和氢探头、质量流量计等实现温度和氮势的精确闭环控制.该设备已成功用于轴套、齿圈和某些精密零件的气体渗氮或气体氮碳共渗.     

烟气保护在普通辊底式热处理炉上的运用

烟气保护式辊底炉是通过向炉内注入烟气来充当保护气体,从而使炉内气氛达到微氧环境的热处理炉。攀钢集团成都钢钒有限公司金堂分公司于2011年7月成功对1台普通辊底式热处理炉进行了改造,并取得良好效果。从炉体结构、烟气循环系统、冷却水系统、含氧量检测、电器及仪表控制系统等方面对将普通辊底式热处理炉改造为烟气保护式辊底炉进行了简要分析。     

Carbon potential and composition of a neutral controlled atmosphere produced from methane and a nitrogen-oxygen mixture

Conclusions Semiempirical equations were obtained and a simplified method was considered for calculation of the carbon potential of a controlled atmosphere produced from methane and a nitrogen-oxygen mixture (air or commercial grade nitrogen) with different oxygen contents in it. A comparison of the results of calculation of a neutral controlled atmosphere produced from methane or from natural gas of a specific composition shows that the error caused by simplification of the method of calculation may in practice not be revealed with the use of production instruments if the natural gas contains not less than 95% CH₄.With the use of the equations obtained a program was set up and used on a computer for calculation of compositions of controlled atmospheres neutral with respect to steels being treated at different temperatures. The calculation data of neutral controlled atmospheres produced from natural gas and commercial grade nitrogen may be used in introduction of them into heat treatment production and the method of calculation and the equations given may be used for determination of the composition of a neutral controlled atmosphere in heat treatment of alloy steels.Gor'kii Polytechnic Institute. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 6, pp. 10–14, June, 1988.     

Heat test for semifinished products of an alloy of the system Al-Mg-Li

Conclusions Development of pores (bubbles) during heating for an alloy of the Al-Mg-Li system at 560°C is due to reaction of the alloy with a moist furnace atmosphere with hydrogen formation. The main role in this is played by magnesium and not lithium or aluminum.All-Union Institute of Aviation Materials Scientific Production Association. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 38–40, February, 1991.     

敞开式环型焙烧炉的综合测试分析

对敞开式环型焙烧炉进行了综合性的测试分析 ,测定了火道中的烟气成分 ,以及火道和阳极的升温曲线 ,估算了焙烧炉的热平衡。指出促使焙烧时热耗增大的主要原因是预热段空气的严重渗漏以及排烟温度的过高。测试分析的结果还显示 ,沥青挥发分若不能及时从阳极逸出到火道中燃烧将严重影响阳极的焙烧质量。     

新型真空脉冲渗氮设备

本文介绍了一种全新的真空脉冲渗氮设备，由加热炉罩、内罩、底座、真空系统、配气系统和控制系统等部分组成，其主要特点在于：采用弹压式触头配电；操作方便；一个加热炉罩可配备多个炉座，能进行脉冲渗氮处理或其它低温化学热处理、真空回火快冷处理、充气保护回火处理等多种工艺加工；热效率高，节能效果显著；控制系统采用了先进的计算机程序控制技术、人机对话技术以及先进的执行元器件如大功率固态继电器等。     

Interaction of steel ShKh15 with controlled atmosphere during annealing

Conclusion Oxidation and decarburization of ShKh15 steel in the process of annealing can be prevented by using endothermal gas, exo-endothermal atmospheres, and purified exothermal gas with the addition of hydrocarbons. The best atmosphere is the exo-endothermal atmosphere with 0.6–0.7% CO₂ in the retort. It is cheap, and its carbon potential can be controlled. Lacking generators of this atmosphere, one can use endothermal gas with the same concentration of CO₂.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 36–38, March, 1976.     

Effect of furnace pressure on intensity of parts carburization in a gaseous atmosphere

Gas carburizing in an endothermal, controlled atmosphere with the addition of natural gas is the standard chernicothermal treatment. The efficiency of the process is determined by its duration (which must be minimal for a given thickness of the layer) and the stability of the characteristics of the diffusion layer (carbon content and thickness). This paper deals with the intensity of parts carburization at different furnace pressures.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 2, pp. 11 – 12, February, 1995.     

Analysis of the operation of exothermic-endothermic generators

Conclusions To ensure high-quality chemicothermal treatment of parts and to increase the service life of generators we recommend continuous furnaces with an independent supply of controlled atmosphere, a constant technological process, weekly burnout of the endothermic gas generator and furnace, and maintenance of constant pressure and temperature of the cooling water.Volga Automobile Factory. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 23–26, May, 1980.     

Processing of Fe3Al and FeAl alloys by reaction synthesis

The effects of powder particle size, alloy composition, and reaction atmosphere on reaction synthesis of binary Fe---Al alloys were studied. Reactions were observed in an open (air) furnace, under static vacuum (in an evacuated quartz tube) and in a dynamic vacuum furnace. Reactions occurring in the open furnace and in the evacuated quartz tube were recorded using high-speed video equipment. High-speed videotapes of reaction synthesis of compacts formed from 45 μm Fe and 10 μm Al particles reacted in air and under static vacuum revealed that an unusual ‘two-stage’ reaction exists in this system under these conditions. Compacts formed from 9 μm Fe and 3 μm Al powder particles do not exhibit a two-stage reaction under any of the conditions examined in this work. The first stage of the two-stage reaction lasts several seconds and starts at round 650 °C. The second stage begins at about 900 °C, reaching temperatures between 1250 and 1350 °C. The progress of the reaction to the second stage is sensitive to the alloy composition and reaction atmosphere. The reaction behavior is explained in terms of thermodynamics and heat transfer, which control the delicate balance between heat accumulation and heat loss during reaction synthesis.     

Research on the Post-reaction Strength of Iron Coke Hot Briquette Under Different Conditions

The utilization of iron coke hot briquette (ICHB) prepared by carbonizing iron ore–coal composite agglomerate made from hot-pressing the mixture of iron ore and blended coal has been considered to be an effective countermeasure to improve blast furnace ironmaking reaction efficiency and to reduce carbon emissions. The strength of ICHB after gasification reaction is overestimated by the Chinese National Standard (GB/T 4000/2008, equivalent to the Nippon Steel Corporation method) and should be evaluated by different methods. In this study, the post-reaction strength of ICHB with the addition of different ratios of iron ore under various conditions was experimentally investigated to illuminate the degradation mechanism of ICHB reacted with CO₂. The results showed that, with increasing the iron ore addition ratio from 0% to 20%, the reactivity of ICHB reacted with CO₂ at 1100°C for 2 h is remarkably increased, due to the catalytic effect of metallic iron in ICHB, while the post-reaction strength is distinctly decreased. Furthermore, stopping at the weight loss ratio of 20%, the strengths of ICHB after reaction at 1100°C under a CO₂ atmosphere and a CO₂/CO=1/1 atmosphere are clearly reduced, from 89.74% to 75.93% and from 85.24% to 73.65%, respectively. Meanwhile, the post-reaction strength of ICHB under CO₂ is greater than that obtained under CO₂/CO=1/1 atmosphere, since there is more time for the reaction gas to diffuse from the exterior to the interior of the ICHB under the latter condition. Additionally, the post-reaction strength of ICHB decreases with increasing weight loss ratio regardless of the reaction gas composition; however, it can be maintained at a high level.     

Coke properties at tuyere level in blast furnace with pulverized coal injection

Coke in the blast furnace experiences great changes in their properties during the blast furnace operation. Pulverized Coal Injection (PCI) into the blast furnace through tuyeres together with oxygen enrichment affect coke properties and blast furnace operation. Using coke sampler at tuyere level, coke samples were collected and analysed at various coal injection rates in the both conventional and co-axial oxygen enrichment. With the help of information obtained from coke sampling experiments, gas permeability resistance index at lower part of blast furnace (LK) and mean size variation of coke were predicted and matched well with the measurements.     

Electromotive force measurements in liquid Ag-In-Pd lead-free alloys

Emf technique was employed to determine indium activities in the liquid Ag-In-Pd alloys using galvanic cells with yttria-stabilised-zirconia as solid electrolyte according to the scheme： kanthal/rhenium, Ag-In-Pd, In2O3 ｜ YSZ ｜ Ni, NiO, Pt. Composition and temperature measurement ranges were limited, because of very steep liquidus surface; 35 compositions for Xpd up to 0.3 were investigated and at temperatures from near-liquidus up to 1700 K. High temperature experiments required special moly furnace to be constructed with unique automatic gas supply system for fumace winding protective atmosphere. Emf readings were taken and recorded by automatic data acquisition system. Linear dependence of emf on temperature was observed for all compositions investigated, and results were approximated by straight line equa- tions. Then In activities were calculated using well-known relations and taking into account correction for thermoelectric power between kanthal and platinum. Results are to be used along with other existing data to perform assessment of the ternary system under accord.     

某汽油加氢脱硫装置引风机系统腐蚀原因及处置措施

通过对汽油加氢脱硫装置加热炉引风机系统腐蚀产物的现场目测、操作条件和介质组成的考察,探讨了该系统的腐蚀原因。结果表明:汽油加氢脱硫装置加热炉引风机系统腐蚀的原因是烟气中的硫化物在低温条件下形成的露点腐蚀,并对此具体问题提出了相应的防护措施。     

氧气底吹铜熔池熔炼过程的机理及产物的微观分析

对氧气底吹熔炼过程气体喷吹行为、造锍熔炼化学反应机理及熔炼炉内热工作状态进行理论分析及水模型实验和取样分析验证。结果表明,氧气底吹气流能使熔体形成均匀的扩散区,实现熔体的搅拌,在气体连续相区和液体连续相区,气液、液液之间的相互作用强烈,为炉内化学反应及传热传质提供了良好的动力学条件;氧气底吹熔炼过程在零配煤的情况下能达到自热熔炼,在节能减排方面,该工艺具有很强的优势;获得了铜渣、冰铜和蘑菇头中各组分的形貌,确定了铜渣、冰铜和蘑菇头的物相组成,渣样主要由冰铜相、磁铁矿相、铁橄榄石相和玻璃体相组成,熔炼内的氧势和硫势分布有利于反应的进行,能有效抑制Fe3O4的形成以及降低渣含铜。     

Oxidation of FeCrAl alloy: influence of temperature and atmosphere on scale growth rate and mechanism

The oxidation behaviour of a FeCrAl alloy with little rare earth content (Y=0.01 wt.%) was investigated. Specimens of this alloy were submitted to long-term oxidation treatments (up to 30 days) at 900 and 1200°C, under gaseous atmospheres containing 21, 10 and 2 vol.% of O₂. The weight gain for unit area was measured vs. oxidation time. The alumina scale growth was found to occur, at least during the first days of treatment, according to Wagner's parabolic law. Afterwards, the layer rate growth decreases down to that expected on the basis of this law. The values of the parabolic rate constant for scale growth (K_p) chiefly depended on the treatment temperature, while only small variations of K_p resulted from significant changes in treatment of atmosphere composition. The morphology and the composition of surface layers were studied by SEM-EDS and XRD analyses. Whatever the treatment temperature, the surface layer contained α-Al₂O₃ and non-negligible amounts of Cr and Fe. The metal/scale interface was always flat, while the morphology of the scale/gas interface changed greatly with temperature. At 900°C an irregular scale/gas interface formed; this was characterised by the presence of long α-alumina whiskers protruding towards the gaseous atmosphere. Contrary, at 1200°C a flat scale/gas interface was observed. These different morphologies can be attributed to different mechanisms of layer growth.     

节能和高效率的离子渗氮炉设计

针对国内离子渗氮炉使用中常见的问题,从减少炉壁散热损失、增加底座承重能力、提高电极连接可靠性等方面提出了改进设计方案.新的设计中取消了大部分的炉壁冷却水夹层,增加了真空隔热层,升温时减少热量损失,降温时充入氮气强制对流冷却,配合快速冷却装置,增加导热系数,加快工件冷却速度.采用圆弧型封头底座,增大炉体承重能力,并改善气体流动的均匀性.输电阴极采用迷宫式屏蔽结构,作为绝缘体的熔铸云母全部屏蔽在钢制外罩之内,不会因放电而损坏;阴极与底座之间采用可靠的密封方式,长期使用不漏气.实际使用表明,新型离子渗氮炉可大大降低热量损失,增加承重能力,维护保养方便;输电阴极使用三年不用拆卸,工作稳定可靠,劳动生产率比常规的离子渗氮炉提高30%.     

Mechanism of structure formation in sintering hard alloys based on alloyed titanium carbide

The use of tungsten-free hard alloys can be widened only if their strength and ductility parameters are improved considerably. This can be attained by alloying alloys of the TiC — (TiN) — Ni - Mo system with Al. Zr, V, Nb. However, many problems associated with formation of the structure and redistribution of the alloying elements in the phases of these alloys in sintering are still not entirely clear. The aim of the present work consists in investigating the process of structure formation in sintering of TiC — 15% Ni — 6% Mo hard alloys that contain aluminum, vanadium, zirconium, and chromium additives introduced into the alloys in the form of complexly alloyed titanium carbides.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 24 – 26, July, 1996.