Ultra-Pure Ferritic Stainless Steels-Grade,Refining Operation,and Application

The grades of ultra-pure ferritic stainless steels, especially the grades used in automobile exhaust system, were reviewed. The dependence of properties on alloying elements, the refining facilities, and the mechanism of the reactions in steel melts were described in detail. Vacuum, strong stirring, and powder injection proved to be effective technologies in the melting of ultra-pure ferritic stainless steels. The application of the ferritic grades was also briefly introduced.

Effect of cold-rolled annealing processes on microstructure and properties of ultra-pure ferritic stainless steel

In this study, the influence of annealing processes for cold-rolled sheets on the microstructure and mechanical performance of ultra-pure 430 ferritic stainless steel was investigated. Thermo-Calc calculation, organization observation, SEM detection,and tensile tests were used to discern the optimal annealing process. It is found that the microstructure is made up by the fine and uniform recrystallized ferritic grains after annealing. The optimum annealing process for ultra-pure 430 stainless steel is 950 ℃ for 90 s. After annealing, the stainless steel can obtain the optimum microstructure,recrystallization texture, and mechanical properties.

Low molybdenum ultra-pure ferritic stainless steel for solar water heaters

In order to meet the demands of service life and the synthetical performance/price ratio of stainless steel in the solar water heater industry, the low molybdenum ultra-pure ferritic stainless steel （FSS） B445J1M was developed at Baosteel. In this study, comparative studies were carried out on the mechanical properties, the formability and the corrosion resistance of B445J1M ,304 and 444 ,and the advantages and application fields of B445J1M were summarized.

Inclusions for Ultra-pure Ferritic Stainless Steels Containing 21% Chromium

As stabilizing elements added into ultra-pure ferritic stainless steels, niobium and titanium react with car- bon and nitrogen to form carbonitrides and have great effects on the ratio of equiaxed zone and the grain size of solidi- fication structure of ingots, which remarkably affect the quality of cold-rolled sheets. Combined with thermodynamic calculation, style and precipitation progress of inclusions in ultra-pure ferritic stainless steels were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy and energy dispersive spectros- copy. The results indicate that the inclusions are mainly Ti-Al-N- O system inclusions in ultra-pure ferritic stainless steels. Al2Oa starts to precipitate firstly and then TiOx and TiN precipitates sequently. The inclusions are mainly single TiN particles and complex inclusions with Al2O3-Ti2O3 as cores and covered with TiN under the condition of 0.31% titanium addition and mainly Al2O3 under the condition of 0.01% titanium addition. A few （Nb,Ti）N parti- cles precipitate because of no enough titanium to react with nitrogen when titanium addition is 0.01 %. In addition, fine Nb（C, N） particles with size of less than 500 nm precipitate at relatively low temperature.

Distribution of TiN inclusions in Ti-stabilized ultra-pure ferrite stainless steel slab

In order to clarify and control the silver defect on surface of cold-rolled sheet of the Ti-stabilized ultra-pure ferrite stainless steel, the distribution of TiN inclusions on the cross section of hot-rolled plate was studied using automated scanning electron microscopy/energy-dispersive X-ray spectroscopy inclusion analysis (ASPEX 1020 system). It was found that the number density decreases sharply from the surface to the center of the hot-rolled plate, whereas the average size increases. Then, the distribution of TiN inclusions on the cross section of continuously cast slab was investigated. Similarly, numerous small-sized TiN inclusions were generated at the subsurface of the slab. The average size rapidly increased and the number density dramatically decreased from the subsurface to 1/4 thickness, while from 1/4 thickness to 1/2 thickness, the increase in average size and the decrease in number density were slight. Thermodynamics results showed that TiN inclusion was formed below the liquidus temperature, which indicated that TiN inclusions could not be formed during secondary refining. Considering the microsegregation of solute elements and the equilibrium of TiN formation during solidification, TiN precipitated in the mushy zone when the solid fraction was close to 0.2. The growth of TiN was analyzed based on the diffusion-controlled growth model. With the increase in cooling rate, the time for TiN growth decreased and the size of TiN inclusions was diminished, which revealed the size distribution of TiN inclusions in the cast slab qualitatively.

Realizing ultra-pure red emission with Sn-based lead-free perovskites

Light-emitting diodes(LEDs)are key for the development of next-generation displays for ultra-high-definition television.Alternative materials beyond organic LEDs are required to meet the color purity standards,while retaining low processing cost and environmental friendliness.Liang and colleagues report in Advanced Science that two-dimensional(2D)tin halide perovskite—efficiently stabilized by H3PO2 incorporation—has great promise for ultra-pure red LEDs.

Characteristics of SEN clogging and adhesive behavior of oxide inclusion during continuous casting of Ti-stabilized ultra-pure ferritic stainless steels

Submerged entry nozzle(SEN)clogging during continuous casting of Ti-stabilized ultra-pure ferritic stainless(Ti-UPFS)steels was systematically investigated via cross-sectional analysis and acid dissolution treatment.The SEN deposit profile was characterized as occurring in three major layers:(1)an eroded refractory layer;(2)an initial adhesive layer comprised an Al_(2)O_(3)-ZrO_(2) composite sub-layer and a dense Al_(2)O_(3)-based deposit sub-layer;and(3)a porous multiphase deposit layer mainly consisting of MgO·Al_(2)O_(3),CaO-Al_(2)O_(3),and CaO-TiOx.The MgO·Al_(2)O_(3)-rich inclusions did not adhere directly to the eroded refractory but were entrapped during the deposit growth.Results of inclusion characterization in the tundish revealed that the MgO·Al2O3-rich particles present in the tundish served as the primary source of clogging deposits.Furthermore,a novel cavity-induced adhesion model by circular approximation was established to explain the effects of complex inclusion characteristics and refractory material type on adhesion force.A high number of small MgO·Al_(2)O_(3) inclusions were expected to accelerate the buildup of clogging deposits.Improving the modification of MgO·Al_(2)O_(3)-rich inclusions in the size range of 2-4μm by Ca treatment was crucial to minimizing the risk of SEN clogging during the continuous casting of Ti-UPFS steels.

HIGH-RESOLUTION PHOTOTHERMAL IONIZATION SPECTROSCOPY ON ULTRA-PURE SEMICONDUCTORS

Ultra-pure semiconductors are very important not only for the detection of nuclear and infrared radiation,but also for the investigation of electronic states of shallow impurities in semiconductors.Almost all of the conventional techniques are not sensitive enough for de-

Comparison of feasibility,microstructure and performance of hybrid laser arc,activated flux tungsten inert gas and friction stir welding for thick plate of innovative ultra-pure ferritic stainless steel

An innovative grade of ferritic stainless steel,ultra-pure 18Cr–2Mo thick plate,was designed and produced for special industrial application.In order to maintain its mechanical properties after joining,three advanced joining methods,hybrid laser arc welding,activated flux tungsten inert gas welding and friction stir welding,were selected and conducted to connect the thick plates.The feasibility of three joining methods,the microstructure and mechanical properties were compared,and the results have demonstrated that the sound joint was successfully produced using the selected parameters through friction stir welding.The obtained hardness and impact toughness of the weld zone were satisfying.In terms of activated flux tungsten inert gas welding,the crack will be created due to microstructural brittleness.And as for hybrid laser arc welding,the weld zone is narrow,and the addition of wire during welding for the top weld metal area leads to higher formation ratio of low-angle grain boundaries,which is beneficial to performance of the joint.However,there is still a weak area in the fusion line of the welded joint.The result has illustrated that the welding of innovative ultra-pure ferritic stainless steel thick plate by friction stir welding is feasible.

不同箍筋形式UHPC梁受扭性能试验

为了揭示箍筋形式对超高性能混凝土(UHPC)矩形梁受扭性能影响,以箍筋形式、间距为变量,开展UHPC梁纯扭试验和计算方法研究。对6根UHPC矩形梁进行纯扭试验。分析受扭梁的失效模式和受扭性能,最后基于螺旋箍筋UHPC梁受力机制,推导极限扭矩计算公式,并与现行规范进行比较。结果表明:不同箍筋形式UHPC矩形梁的失效模式均为延性破坏;箍筋间距相同时,螺旋箍筋梁的裂缝分布更密集;极限扭矩、扭转延性及屈服刚度与箍筋间距呈负相关,螺旋箍筋屈服刚度提升更为显著;本文提出的螺旋箍筋UHPC梁极限扭矩公式计算值与试验值结果吻合良好,表明螺旋箍筋UHPC梁具有较好的抗扭性能,提出的计算公式可较好地预测极限扭矩。

超纯无烟煤导电性影响因素

为研究无烟煤自身的导电特性,提高其导电性能,使无烟煤成为填料和电极材料的一部分,采用酸溶法制备了灰分0.13%的超纯无烟煤,采用粉末电阻率仪探索了含水率、灰分、压强、粒度及矿物质成分对超纯无烟煤导电性的影响规律。结果表明,无烟煤电导率随含水率和压强的升高呈上升趋势。随灰分降低电导率逐渐升高。灰分低于1.0%时,电导率随灰分降低而急剧升高。压强4.00 MPa、含水率6.21%、粒度0.2~0.1 mm,灰分降至0.13%时,无烟煤导电性最佳,其电导率为1.44×10^(-7)S/cm。研究范围内,粒度对无烟煤电导率影响较小。煤中常见矿物质的电导率顺序为:黄铁矿>高岭石>二氧化硅>碳酸钙>硫酸钙;黄铁矿电导率最高,达1.32×10^(-2)S/cm。无烟煤电导率随黄铁矿含量增加呈升高趋势,而随其他矿物质含量增加呈降低趋势。采用响应曲面模型优化正交试验结果,获得了无烟煤电导率与含水率、灰分及粒度之间的二次回归方程。含水率和灰分对无烟煤电导率测试结果的影响显著,其中灰分对电导率的影响程度最大,含水率次之,粒度最小。

超纯液相环境纳米金属催化降除多元微污染物特性与机理

集成电路超纯水制备系统的精处理工艺段提供了微污染控制的保障环境。在痕量污染控制环境下,以铂族金属为代表,构建金属纳米粒子对氢氧合成反应的复相催化体系,可以实现多元微污染物的联合降除,进而满足3nm制程超纯水制备系统溶解气体和痕量氧化剂的控制要求。研究阐述和总结了氢氧合成反应的四种反应机制和催化作用机理,重点讨论了金属表面结构、活性位点、形貌尺寸、合金组分、载体性质、液相反应环境对各反应途径催化活性及选择性的密切影响,形成了洁净水相氢气氧化反应的边界条件,对于金属纳米粒子在超纯水领域的应用研究具有导向意义。

河北某普通磁铁矿制备超纯铁精矿试验研究

河北某普通磁铁矿TFe品位为65.25%,矿石性质结构简单,具有制备超纯铁精矿的潜力。研究采用多元素及X射线衍射图、物相分析等方法对原矿进行了工艺矿物学研究,并在此基础上对其进行了提纯试验。结果表明,原矿经过弱磁选粗选后,在磨矿细度-0.038 mm占85%的条件下经弱磁选再选、磁选柱精选得到TFe品位为71.31%的磁选柱精矿以及TFe品位68.12%、产率为3.32%的磁选柱铁尾矿。通过进一步考察药剂制度和工艺流程对铁矿精矿品位、回收率等选别指标的影响,确定了合适的药剂制度。而后磁选柱精矿经1粗3精反浮选降硅工艺试验流程,最终可获得含TFe品位71.95%、综合回收率为80.50%的超纯铁精矿,浮选尾矿TFe品位68.17%符合普通铁精矿标准。通过对选别产品进行试样化学成分分析及残余药剂测定,进一步证明该工艺流程可以实现超纯铁精矿的制备。该工艺在抛尾率为10.79%条件下,将原矿样的73.04%转化为超纯铁精矿,对这一地区超纯铁精矿的制备具有重要的指导意义,也为国内其他地区磁铁矿制备超纯铁精矿的研究提供了一定的参考价值。

蓝莓复合果泥超高压和热杀菌的比较分析

以蓝莓、草莓和苹果为原料,通过感官评价分析,研制出一款蓝莓复合果泥。利用超高压(UHP)和热杀菌(TS)处理果泥,分析处理前后和4℃贮藏40 d内其微生物、理化指标、色泽、花青素、香气和流变特性的变化。结果表明,两种处理后果泥菌落总数、大肠菌群和霉菌均未检出,贮藏40 d时仍符合食品标准限量。pH值在处理后和贮藏期内都显著降低(P<0.05)。可溶性固形物在UHP处理后无显著变化(P>0.05),TS处理后显著增大(P<0.05),贮藏结束时均为7.80°Brix。TS处理后果泥花青素含量显著降低(P<0.05),UHP组无显著变化(P>0.05),贮藏期间,UHP组花色苷含量显著高于TS组。UHP和TS组果泥贮藏期间ΔE最大值分别为1.26和3.47,TS组果泥贮藏时出现明显颜色变化。电子鼻结果表明UHP比TS能更好地保留果泥的香气成分。流变仪结果表明UHP组果泥贮藏期间具有更好的稳定性。综上,UHP对蓝莓复合果泥的品质保存效果好,是一种适用于蓝莓复合果泥加工的杀菌方式。

纯钛极薄带微流道刚柔复合模成形工艺

纯钛因存在延展性和各向异性导致成形性能差,难以成形高深宽比微流道。针对上述问题,提出了纯钛极薄带微流道刚柔复合模成形工艺,以提高纯钛极薄带成形性能,成形更大深宽比、壁厚更均匀的纯钛双极板微流道。通过单向拉伸实验测试了纯钛极薄带力学性能参数,采用刚柔复合模成形工艺研究了纯钛极薄带微流道成形极限,采用光学显微镜对微流道深度、深宽比和壁厚进行了测量分析。结果表明,纯钛极薄带存在显著的各向异性,TD方向r值最大为2.56,选择该方向垂直于微流道进行成形实验;在柔性垫厚度为0.35 mm时,微流道具有最大深宽比为0.53,较传统刚模微流道成形极限提高了26.7%,并显著提高了微流道壁厚分布均匀性。

超纯水系统国产除硼树脂的筛选及应用研究

硼是超纯水水质的关键指标之一,可通过除硼树脂去除,但市场上除硼树脂主要被国外企业垄断,国产树脂应用少,运行参数和稳定性不明确,市场推广难度大。通过除硼树脂静态吸附试验和连续流中试,开展对典型国产除硼树脂的性能评价和项目应用研究。根据吸附容量、有机碳溶出、再生稳定性、长期运行稳定性、采购成本及货源稳定性等多元评价指标,筛选出性能优异的国产除硼树脂,硼吸附量可达5.1 g/L,TOC溶出量低至3.01μg/L,经过10次再生后除硼吸附量为新树脂的97.84%,在中试线实现了连续9个月高标准除硼和稳定运行,产水硼质量浓度稳定低于10 ng/L。将筛选出的国产树脂A及运行参数应用于实际工程中,实现了超纯水系统稳定除硼至50 ng/L以下,并长效稳定运行。

河北某低品位磁铁矿石制备超纯铁精矿试验研究

为探究河北某低品位磁铁矿石制备超纯铁精矿的可行性,以传统工艺矿物学研究方法为基础,结合化学分析、扫描电镜等手段,对该矿石化学组成、矿物组成、磁铁矿嵌布特征等进行了系统研究,矿石中磁铁矿平均含铁71.82%。采用磁浮联合工艺进行试验研究,在一段磨矿细度为-0.074 mm55%,二段磨矿细度P_(80)为25μm的条件下,经阶段磨矿—阶段弱磁选流程,可获得TFe品位为70.18%的弱磁精矿;对弱磁精矿进行三段磨矿(P_(80)=21μm)后,以胺类捕收剂CYA-20和淀粉类抑制剂CYZ为选别药剂,经1粗2精反浮选闭路流程,可获得超纯铁精矿TFe品位71.64%、对原矿回收率62.56%,普通铁精矿TFe品位66.13%、对原矿回收率22.48%的选别指标。研究成果为该磁铁矿石的高附加值利用提供了依据。

国产高密度聚乙烯在电子级化学品包装桶上的应用研究

将中韩石化高密度聚乙烯HD570制备成200升包装桶,并在电子级化学品包装方面进行试用研究。结果显示HD570满足堆码和跌落测试,在电子化学品盛装测试中金属离子析出结果合格,但颗粒物析出结果不合格。通过熔指仪、万能材料试验机测试等手段比较了中韩HD570与包装桶中外层料1158P的物理性能,表明中韩HD570取代中外层料1158P在产品拉伸屈服应力、弯曲模量及加工性能方面更优。进一步对HD570包装不合格的原因进行探究,多方面比较了HD570和进口料NH8D01A的性质,显示HD570原料在产品灰分和产品结晶度上低于NH8D01A,低分子量聚合物含量高于NH8D01A,再加上添加剂配方的影响,导致HD570在电子级化学品包装颗粒物析出测试不合格。本研究为替代进口的超纯内层料开发提供了思路和建议。

反渗透膜市场及技术研究

反渗透是一种膜分离的过程,以膜与膜之间的压力差为推动力,是渗透的逆过程,也是目前最为先进的分离技术之一。通过多方走访与市场调研,分析了国内反渗透膜产能不足及技术垄断的现状,针对市场问题提出了相应的技术解决方案,并进一步探讨了反渗透膜技术未来发展的趋势。

ICP-MS快速检测超纯水中43种元素新方法

电感耦合等离子质谱法(ICP-MS)检测超纯水中43项超痕量金属杂质。将传统多仪器简化成一台ICP-MS,多次数实验减至一次,1天检验周期压缩至2 h。保证检验准确性及精密度的同时,达到降本增效的目的。实验结果证明:新检测方法实验校正曲线线性相关系数>0.999;检验回收率99.1%~104.8%;实验数据相对标准偏差<5%。该方法操作简便,分析速度快,结果准确可靠,可满足超纯水的43项元素快速检测需求。