预喷丸对H13钢气体渗氮行为的影响

采用质量增量分析、剖面金相分析和显微硬度测量等方法研究了预喷丸处理对H13钢气体渗氮动力学与渗氮层性能的影响。结果表明，预喷丸处理对H13钢气体渗氮有明显的催渗作用，这种催渗作用在白亮层尚未形成的渗氮初期最为明显，随着渗氮温度升高，预喷丸处理的催渗效果显著提高。试验数据还表明，预喷丸催渗所增加的氮原子一方面使渗氮层加深；另一方面使扩散层固溶氮浓度和／或氮化物沉淀相密度提高。测量表明，预喷丸催渗条件下形成的渗氮层的硬度明显高于普通气体渗氮。     

碘对氮碳共渗钢件组织和硬度的影响

在６００￣７００℃地不同材料进行了催渗氮碳共渗，对试样进行了金相分析，硬度测定，对渗层进行电子探针成分析。结果表明，在共析温度以下进行催渗氮碳共渗，具有渗速快、渗层硬度高的特点；化合物随催渗温度升高而增厚，致密碳共渗后快冷，在渗层获得含氮碳的马氏体组织，用该工艺处理轮模具等零件，变形小，耐磨性高，零件的寿命高。     

净化催渗离子渗氮及渗层性能研究

采用阶段性通入含氮气氛的方法,探究净化处理对N80钢离子渗氮的影响。采用金相显微镜、显微硬度计、XRD分析离子渗氮层。结果表明:净化处理对离子渗氮具有明显的催渗作用。净化处理的催渗作用随着净化时间的延长和净化温度的升高而增加。但处理时间过久或温度过高,起不到催渗作用,反而造成金属表面脱碳,影响离子渗氮效果。净化处理20 min后550℃离子渗氮6 h,渗氮层厚度约0.55 mm,比未经净化处理的离子渗氮层厚约0.2 mm,且渗氮层硬度梯度减小,韧性提高。     

AISI420不锈钢表面低温渗氮层组织结构和耐蚀性能

对AISI420不锈钢进行低温等离子体渗氮处理,采用金相观察、X射线分析等手段对渗层组织结构进行表征,利用显微硬度仪以及腐蚀极化曲线等对渗层硬度和耐蚀性能进行测试。结果表明,不锈钢表面渗层组织均匀,渗层厚度随着温度和时间的增加而增加,渗层表面主要由Fe_4N和少量的过饱和含氮α相组成。渗氮后,不锈钢硬度明显增加,且随着时间的延长,渗层硬度升高;渗氮4 h和8 h后的试样耐蚀性均略有下降,但处理12 h后的试样耐蚀性升高,且经渗氮处理后,不锈钢表面形成钝化膜的半导体特性由未处理不锈钢的p型转变为n型。     

38CrMoAl钢钛催渗等离子氮化工艺研究

目的 探究38CrMoAl钢钛催渗等离子渗氮工艺及机理.方法 在其他工艺参数确定的情况下,通过常规等离子渗氮与钛催渗等离子渗氮处理对比试验,研究38CrMoAl钢钛催渗离子渗氮处理随渗氮时间的变化规律.对试样进行表面硬度、渗层深度检测和显微金相组织与SEM形貌的观察,探究不同处理工艺的催渗效果及钛催渗等离子渗氮的机理.结果 在渗氮的前3 h,渗氮层厚度增加明显,当渗氮时间超过3 h后,其氮化层的厚度便趋于饱和.对比不同时间(3、5、8 h)钛催渗等离子渗氮的表面硬度,差距不大.综合得出38CrMoAl钢在渗氮温度535℃、氨气流量2.0 L/min的工艺参数下,钛催渗等离子渗氮效率最优的渗氮时间为3 h,其表面硬度为1160.8HV,渗层深度为300μm,优于常规离子渗氮8 h的作用效果.结论 38CrMoAl钢试样经过钛催渗等离子渗氮后,渗层的表面硬度和深度明显高于常规离子渗氮.钛的加入可以促使合金元素向表面富集,有利于表面合金化,提升渗氮效率,增强渗氮效果.     

热循环离子渗氮及其强渗作用

用正交试验法研究了３８ＣｒＭｏＡｌＡ钢热循环离子渗氮的特点及其强渗作用。结果表明，渗氮过程受循环参数控制，渗层组织呈层状结构，渗层生长曲线存在长达６ｈ的亚速线性段；在强渗工艺下，该段斜率明显增大。这一动力学特性看来是由热循环催渗和离子轰击加速氮原子扩散的有利作用所致，从而使深层渗氮时间比恒温或分段渗氮缩短了２／３￣１／２。     

预氧化催渗气体渗氮的研究

研究了预氧化对气体渗氮渗层深度和动力学过程的影响，试验找出了在５４０、５８Ｑ及６２０℃不同温度下渗氮层深度和氧化时间的变化关系．研究发现，短时预氧化对气体渗氮具有强的催渗作用；据此，提出了预氧化一渗氮循环处理工艺，并获得较好效果．     

42CrMo钢的钛催渗等离子渗氮工艺

研究了不同渗氮时间下钛元素对42CrMo钢常规离子渗氮工艺的作用效果,表征分析了不同渗氮工艺下试样表面的渗层组织及性能。结果表明,钛催渗离子渗氮试样的表面硬度和渗层深度均明显高于常规离子渗氮。在535℃×3 h的工艺条件下,钛催渗离子渗氮试样渗层的表面硬度达到887.4 HV0.2,渗氮层厚度约为400μm。钛元素的加入促进了氮元素的渗透和扩散,在试样表面生成高硬度化合物TiN。相较于相同保温时间下的常规离子渗氮,钛催渗离子渗氮试样表面硬度提高了60 HV0.2,渗层厚度增加了80μm,渗氮效率提升了约25%。与常规离子渗氮相比,钛催渗离子渗氮工艺具有显著优势,不仅有利于改善渗层组织性能,增强渗氮效果,还提高了渗氮效率,使渗氮周期明显缩短。     

不锈钢的高氮表面处理

不锈钢这一级的钢子１０５０～１１５０℃温度范围内，在氮气中氮进行了升扩散，淬火得到高氮马氏体或高氮奥氏体渗层，低碳，低氮马氏体类型可能是含氮淬硬层形成硬的马氏体渗层，可用于不锈钢轴承和工具；双相不锈钢处理后获得高强度奥氏体渗层，可以减轻泵的气蚀。与碳元素相比，溶入的氮可以提高耐蚀性，该工艺与普通渗氮处理的本质区别在于 溶入奥氏体中而不是在铁素体中沉淀析出。     

AISI431不锈钢表面“膨胀”α相层的制备和性能

对AISI431马氏体不锈钢进行低温等离子体改性处理,通过金相观察、X射线分析等对渗层组织结构进行表征,利用显微硬度仪以及腐蚀极化曲线等对渗层硬度和耐蚀性能进行测试。结果表明,通过低温改性处理,均可在不锈钢表面获得含有"膨胀"α相的渗层,其中渗氮处理后表面主要含Fe4N和含氮"膨胀"α相,渗碳处理后表面主要为含碳"膨胀"α相,且渗氮层厚度明显大于渗碳层厚度。经低温改性处理后,不锈钢表面硬度显著提升,且渗氮层硬度高于渗碳层硬度。然而,在本试验条件下渗氮渗碳的不锈钢耐蚀性能均略有下降,和渗氮相比,渗碳处理后的试样耐蚀性能更差,且在腐蚀过程中,两类渗层表面所产生钝化膜均为具有n型半导体特性。     

Nitriding of steel in potassium nitrate salt bath

A potassium nitrate salt bath has been used for nitriding of interstitial-free steel. The nitriding behavior can be reasonably well described by nitrogen diffusion in iron. Most nitrogen is dissolved interstitially. During nitriding, a slight oxidation of the steel surface also takes place. The nitrided specimen achieves a pronounced solid–solution strengthening.     

稀土在离子渗氮中的氧化对催渗效果的影响

利用Ｘ射线衍射仪和扫描电镜研究了稀土催渗离子渗氮过程中,稀土与氧之间的作用对催渗效果的影响。结果表明：用新稀土块进行催渗时,稀土易与渗氮气氛中的氧结合,使气氛中的大部分氧被清除,大大削弱了氧对不参氮的阻碍作用,提高了渗速,稀土遥这种除氧作用是稀土催离子渗氮的又一重要原因,用过的旧稀土块催渗效果差,原因是在其表面形成了一怪厚的氧化物,使稀土的催渗作用不能充分发挥,若将这层氧化物剥去后再使用,稀土的催     

Inhibierung der Korrosion von Messing 63/37 in Ammoniumchloridlösungen

Inhibition of the corrosion of 63/37 brass in ammonium chloride solutions Potassium chromate, dichromate, ferrocyanide and thiocynate have been investigated as inhibitors corrosion 63/37 brass in 0.005 M and 0.01 M ammonium chloride solutions. Nearly complete protection is afforded to brass by potassium chromate at all the durations studied. Potassium thiocynate is more effective in 0.01 M ammonium chloride rather than in 0.005 M ammonium chloride. In the case of potassium thiocyanate and potassium ferrocyanide, the efficiency is maximum at the optimum concentration of the inhibitor, further increase in inhibitor concentration induces a decrease in inhibitor efficiency. Both these substances afford protection by mixed control. Potassium dichromate is a mixed type of inhibitor with a predominant action on the local cathodic areas. Potassium chromate retards the corrosion by influencing both cathodic and anodic reactions, cathodic to a greater extent.     

Influence of initial heat treatment of 17-4 PH stainless steel on gas nitriding kinetics

Results of the investigation of nitrided layers on 17-4 PH type precipitation hardening stainless steel are presented in this paper. The layers have been produced in the process of gas nitriding in a partly dissociated ammonia at temperatures between 410 and 570 °C. Hydrogen chloride admixture to active atmosphere was used as a surface activator. Structure of the nitrided layers were examined using scanning and transmission electron microscopy, X-ray microanalysis (EDX and WDX), and X-ray diffraction. The influence of the initial steel heat treatment on the nitriding kinetics has been considered. 17-4 PH stainless steel was nitrided at various heat treatment conditions, i.e. after solution treatment or ageing at different temperatures. The influence of precipitation processes taking place during the heat treatment before nitriding on the diffusive process kinetics was proven. It was found that, that increasing of steel ageing temperature up to 600 °C before nitriding effects on an increasing of the nitriding kinetics.     

Recovering germanium from coal ash by chlorination with ammonium chloride

A new process of enriching germanium from coal ash was developed.The process involves in mixing the coal ash and ammonium chloride and then roasting the mixture to produce germanium chloride that is then absorbed by dilute hydrochloric acid and hydrolyzed to germanium oxide.The germanium recovery reached to 80.2% at the optimum condition:mass ratio of NH4Cl/coal ash is 0.15,roasting temperature 400℃ and roasting time 90min.     

Modeling the Gas Nitriding Process of Low Alloy Steels

The effort to simulate the nitriding process has been ongoing for the last 20 years. Most of the work has been done to simulate the nitriding process of pure iron. In the present work a series of experiments have been done to understand the effects of the nitriding process parameters such as the nitriding potential, temperature, and time as well as surface condition on the gas nitriding process for the steels. The compound layer growth model has been developed to simulate the nitriding process of AISI 4140 steel. In this paper the fundamentals of the model are presented and discussed including the kinetics of compound layer growth and the determination of the nitrogen diffusivity in the diffusion zone. The excellent agreements have been achieved for both as-washed and pre-oxided nitrided AISI 4140 between the experimental data and simulation results. The nitrogen diffusivity in the diffusion zone is determined to be constant and only depends on the nitriding temperature, which is ~5 × 10^?9 cm²/s at 548 °C. It proves the concept of utilizing the compound layer growth model in other steels. The nitriding process of various steels can thus be modeled and predicted in the future.     

稀土含量对38CrMoAl钢渗氮层性能的影响

为了克服38CrMoAl钢渗氮速度慢,渗层脆性大,稀土添加到渗氮气氛中只能作用于工件表面等缺点,研究了38CrMoAl钢中不同稀土添加量对渗氮层性能的影响,并初步分析了其影响机制。研究结果表明：稀土对38CrMoAl钢渗氮具有明显的催渗作用,且能提高渗层性能。原因是稀土加入钢中后,引起周围铁原子的点阵畸变,有利于氮原子的吸附和扩散,且稀土易与渗氮气氛中的氧结合,削弱了氧对渗氮的阻碍作用;同时稀土的晶粒细化、固溶体强化、微合金化也是其改善渗层性能的重要原因。     

超声波导入杆与振动子之间的共振度对铝合金铸锭组织的影响及其模拟试验

研究了在超声波导入杆与振动子之间的各种共振度下,超声波振动对Al Si合金,Al Zn合金铸锭组织的影响,分析了超声波对铝合金铸锭细化的作用效果。结果表明:随着超声波导入杆与振动子之间的共振程度的增加,铸锭的细化效果也大幅度增加。并用氯化铵水溶液对这一结果进行了模拟试验。     

Anode plasma electrolytic nitrocarburizing of steel in an aqueous electrolyte based on glycerol,ammonium nitrate,and ammonium chloride

The mechanism of transport of saturating components from the electrolyte into the treated material during the anode nitrocarburizing of steel in an electrolyte containing glycerol, ammonium nitrate, and ammonium chloride has been described. The effect of the electrolyte component concentrations and treatment conditions on the pattern of formation and properties of the diffusion layers has been determined. The possibility of preparing a nitrocarburized layer with a thickness of up to 0.2 mm and a surface microhardness of up to 870 HV has been shown.     

石灰炉炉灰提取氯化钾试验研究

在系统分析石灰炉炉灰物化指标的基础上,研究了采用石灰炉炉灰,利用水浸法提取氯化钾的工艺方法。试验结果表明:炉灰是一种良好的提取钾盐原料,氯化钾回收率高达90.68%。