低碳铝镇静钢表面缺陷控制

介绍了低碳铝镇静钢轧后容易出现的几种主要钢质缺陷,并对缺陷的产生原因进行了初步分析,通过改进钢水的化学成份,降低钢水氧化性,适当延长钢水炉外处理时间和降低浇铸时中间包水口吹氩量,可有效减少低碳铝镇静钢的轧后缺陷率.     

RH精炼脱氧过程铝含量预报模型

在河北钢铁集团唐钢公司RH生产实绩的基础上,采用多元线性回归的计算方法,建立了RH精炼铝脱氧过程钢水溶解铝含量的预报模型.模型计算结果表明,RH脱碳结束后钢水中的溶解氧含量越高,脱氧后钢水中的溶解铝含量越低;适当高的钢水温度有利于提高钢水溶解铝含量;随钢水脱氧加铝量的提高,钢水中的溶解铝含量逐渐增大.钢水溶解铝含量的实测值基本围绕着预报值波动,模型较好地预测了河北钢铁集团唐钢公司RH精炼铝脱氧后钢水中的溶解铝含量,研究开发的模型可信.     

LF炉无铝脱氧的工艺实践

介绍了承钢120t系统对钢中酸溶铝没有要求钢种的LF炉无铝脱氧实践。精炼过程中采用硅钙钡、硅钙粉、电石、碳化硅等对钢水进行无铝脱氧工艺,减少了钢水中的Als和Al2O3,精炼过程中加入Al2O3含量较低的精炼渣系,提高炉渣碱度,降低SiO2的活度,大幅提高硅的脱氧能力;优化钙处理工艺,对钢水进行深脱氧,通过夹杂物变性控制夹杂物的形态和尺寸。实践证明,对钢中酸溶铝没有要求的钢种采用无铝脱氧工艺后,没有降低钢水质量,提高了钢水可浇性,吨钢精炼费用降低2．96元／t。     

定径水口浇铸电炉铝脱氧钢防水口堵塞

分析研究中间包定径水口堵塞问题,在没有降低钢水中铝含量和改变水口材质的条件下,优化与水口堵塞有关的工艺制度和正确控制与水口堵塞有关的工艺参数,解决了中间包定径水口浇铸电炉铝脱氧钢水口堵塞问题.     

为了减少钢中脆性Al_2O_3夹杂物,国外一些厂家采取的措施

<正>a.先用硅脱氧降低钢中溶解氧含量,然后再用铝终脱氧。但所生成的SiO2起到了二次氧化源的作用,必经降低SiO2的活度以防止其与钢水中铝发生反应。对于w[si]=0.10%~0.3%的轴承钢,控制碱度在4以上可以保持炉渣中SiO2的稳定。实际操作中,炉渣碱度常控制在5以上。b.用碳代替部分铝进行钢水粗脱氧。出钢     

焊接用盘条H08MnA的生产实践

介绍承钢提钒炼钢一厂采用铁水提钒、半钢炼钢、LF精炼、塞棒保护浇注生产H08M nA的工艺实践.通过提高转炉终点命中率减少钢水过氧化,将钙铝比值控制在0.10～0.14,强化连铸保护浇注,解决了H08MnA钢水可浇性问题;通过减少转炉下渣量、控制加铝和精炼时间,有效降低了钢水回硅.试制炉次成分控制满足钢种要求,铸坯综合合格率为100％.     

LF炉精炼工艺优化

精炼工序采用铝脱氧易产生钢水下流不好现象,影响生产顺行;铝脱氧的精炼成本较高,精炼周期较长.对Als没有要求的钢种,在转炉出钢过程中加小粒灰、热态精炼钢渣再利用、使用非铝基脱氧剂和根据钢中Als含量进行钙处理等措施,钢水可浇性连续11个月达到100％,缩短了精炼周期,降低了电耗、电极消耗和渣料消耗等.     

莱钢近终形异型坯铝脱氧工艺的研究与应用

莱钢针对供异型坯连铸机钢水采用硅、锰脱氧存在脱氧效果差、炉渣流动性差、炉渣碱度低及精炼造渣困难等一系列问题。利用铝脱氧剂脱氧快、脱氧效率高的特点,提高异型坯钢水的脱氧效率和钢水质量;优化精炼渣系功能,采用夹杂物全流程控制技术,提高钢水纯净度;优化精炼钙化处理效果,加强对夹杂物进行变性处理,提高钢水可浇性;强化连铸机铝脱氧钢水的无氧化浇注技术,解决水口结瘤问题。该措施确保了异型坯连铸机铝脱氧工艺生产的顺行,提高了铸坯质量,降低了生产成本。     

唐钢RH精炼碳氧平衡研究与应用

研究了唐钢RH精炼在不同真空度条件下的碳氧平衡条件,探索了进站钢水碳含量、终脱氧位对不同真空度下出站钢水碳含量的影响规律,分析了终脱氧位对钢水洁净度的影响。研究结果表明,通过调节钢水的终脱氧位稳定不同真空度条件下RH出站钢水的碳含量。提高真空度,降低钢水终脱氧位可以降低RH精炼后期铝脱氧Al2O3夹杂物的生成,提高钢水洁净度。     

改善钢水流动性的生产技术

在对水口堵塞物检测分析的基础上,从提高钙处理效果、降低钢水氧化性、优化耐火材料成分、改变加铝方式和加强精炼过程的控制等方面研究了钢水流动性变差的原因。通过采取相应的技术措施,有效地改善了钢水流动性,降低了水口堵塞的发生率。     

转炉冶炼低碳钢脱氧合金化工艺优化

通过对碳-氧反应机理的研究分析,对转炉冶炼低碳钢脱氧合金化工艺进行优化改进。优化后,转炉冶炼低碳铝镇静钢在出钢前期采用碳粉代替部分铝进行钢水预脱氧并且在出钢前期加入低价的高碳锰铁进行合金化,利用碳-氧反应脱除高碳锰铁中的碳。结果表明:铝块消耗平均降低了0.24 kg/t,锰铁合金成本降低了2.56元/t,取得了较好的经济效益。     

Mechanical Behavior of CFRP Rod Anchors under Tensile Loading

This paper presents the results of an experimental and numerical study to examine the mechanical behavior of carbon fiber reinforced polymer rods gripped by a wedge anchor, comprised of an aluminum sleeve, four stainless steel wedges, and a stainless steel barrel. The carbon fiber reinforced polymer rod-anchor system was tested under monotonic and cyclic loading conditions. In the static load tests, the effect of presetting loads, usage history, and sleeve material were investigated. Presetting load levels of 50, 65, 80, and 100 kN were used, and tests were conducted with new and reused anchors. Aluminum and copper sleeves were considered. As the presetting load increased, the displacement (or slip) of the rod and sleeve decreased. No significant effect of reusing the anchor was found other than replacing the sleeve. Anchors with copper sleeves performed poorly at low presetting loads, in comparison to aluminum sleeves. Cyclic load tests were conducted on anchors using aluminum sleeves with a presetting load of 80 kN. The effects of cycling on the rod and sleeve displacement were minor for different mean stresses and stress ratios. A finite-element model, consisting of three contact surfaces, was applied to simulate the anchor components; the displacement of the rod compared well with experimental results.     

The dynamic oxidation of aluminum and its alloys

In order to investigate the rate of oxidation of liquid aluminum and its alloys under conditions similar to those found industrially, carbon dioxide was bubbled through the melt and the change in gas composition monitored using a mass spectrometer. It was found that the dynamic oxidation of aluminum was a function of the carbon dioxide partial pressure and was considerably faster than oxidation under quiescent conditions. For alloys containing an appreciable amount of magnesium, the magnesium oxidized in two stages. The carbon dioxide was first reduced to carbon monoxide and then to carbon. At lower magnesium levels, aluminum is preferentially oxidized, but the reduction of the carbon dioxide proceeds only as far as carbon monoxide.     

S08A自耗电极及电渣重熔工艺试制

本文论述了优化电炉配料、选用优质石灰、精选萤石、电炉出钢换渣工艺;电渣重熔采用四元渣系,选用提纯萤石,重熔过程全程氩气保护铝粒脱氧等工艺措施,生产出低碳、低硅、低氮及残余、五害元素符合要求的自耗电极及电渣锭,经轧制成材检验低倍组织及非金属夹杂物符合技术协议要求。     

CFRP?泡沫铝夹芯结构控制臂优化设计

为满足控制臂的轻量化设计需求,提出了一种采用碳纤维复合材料（CFRP）?泡沫铝夹芯结构的汽车悬架控制臂,并对CFRP面板进行结构优化设计。通过泡沫铝准静态压缩试验验证了泡沫铝六面体胞孔模型的准确性,利用CFRP力学性能试验获得了碳纤维复合材料的性能参数,设计一种由CFRP?泡沫铝夹芯结构本体和铝合金连接件组成的悬架控制臂,控制臂本体与连接件之间采用胶?螺混合连接。在此基础上,建立CFRP?泡沫铝夹芯结构控制臂有限元模型,利用多层次优化方法对CFRP面板进行铺层优化。结果表明,相较于钢制控制臂,优化后夹芯结构控制臂的质量减少了26%,同时强度、刚度和模态性能都有所改善。      

Leaching ion adsorption rare earth by aluminum sulfate for increasing efficiency and lowering the environmental impact

The leaching efficiency(LE) of ion adsorption rare earth(IARE) by the sulfate and chloride of ammonium,magnesium and aluminum were comparatively determined using column leaching method. It is found that at equal equivalent concentration of cation, the LE of IARE by aluminum sulfate is the highest, and the zeta potential of clay mineral particles in the tailing is near to zero, which means a lower risk of landslide and pollutant emission. Furthermore, the optimum concentration of aluminum sulfate is determined to be0.02 mol/L, which is much lower than that of ammonium sulfate and magnesium sulfate. To reduce the production cost and environmental impact, we proposed a multi-stage leaching process, which was firstly leaching with ammonium sulfate and then with aluminum sulfate, following by water washing and lime neutralizing. With the ratio of ammonium sulfate to aluminum sulfate varying from 1:0 to 0.5:0.5, the residual ammonium in tailing decreases from 11.2% to 0.6%, however, the LE of RE shows an optimum value at 0.8:0.2. By neutralizing the pH of tailing with lime water to over 6, the ion concentration in water rinsing solution can meet the requirement for water discharge. At the same time, the zeta potential of clay particles is found to be around-5 mV, means a relatively lower risk of landslide. These facts indicate that the LE of IARE can be increased and the danger caused by tailings landslides and pollutant emissions can be reduced by replacing ammonium sulfate with aluminum sulfate as leaching reagent.     

纳米碳管铝基复合材料组织与性能的研究

试验采用搅拌铸造法制备了纳米碳管增强铝基复合材料,对其显微组织、硬度、抗拉强度和电阻率进行了研究.结果表明:纳米碳管的加入能够细化复合材料晶粒,表面镀铜后可以抑制基体与增强体之间的界面反应,避免脆性碳化物的生成;复合材料的硬度和抗拉强度随着纳米碳管加入量的增加先增加后减小,纳米碳管的质量分数为1.0%时,达到最大值,与基体相比分别增加了34.8%和34.4%;纳米碳管的加入对基体的导电性影响不大.     

高碳铬铁合金固相显微结构及破碎性能

为了研究高碳铬铁合金在浇注过程添加硅铁粉和铝后固相显微结构及破碎性能变化,在0.2 t多功能炼钢中试炉重熔某铁合金公司生产的高碳铬铁,浇注时分别添加硅铁粉和铝,分析重熔的常规高碳铬铁、添加铝及硅铁粉的高碳铬铁的固相显微结构,并将样品经颚式破碎机破碎。结果表明,高碳铬铁显微结构主要由(Cr,Fe)7C3固态相和(Cr,Fe)7Si固态相组成,有部分TiN、MnS和Al2O3夹杂物析出,常规高碳铬铁中未发现Al2O3夹杂物,而添加硅铁粉和铝的高碳铬铁中均析出了Al2O3及TiN夹杂物;添加铝的高碳铬铁组织致密,气孔率小,而常规高碳铬铁存在大量裂纹和孔洞,组织疏松,添加硅铁粉的高碳铬铁介于两者之间;经颚式破碎机破碎后,常规高碳铬铁、添加硅铁粉的高碳铬铁和添加铝的高碳铬铁破碎后粉末率分别为13.2%、11.7%和9.5%。     

铝用炭素工业碳排放核算方法

铝用炭素材料是氧化铝—冰晶石熔盐铝冶炼生产过程中不可或缺的重要材料之一,分为铝用炭素阳极材料与铝用炭素阴极材料,其生产过程中造成大量二氧化碳排放,包括因物理化学反应造成的二氧化碳排放、燃料燃烧造成的二氧化碳排放,以及因能源消耗造成的二氧化碳排放。但现有文献中涉及铝用炭素工业碳排放具体核算的很少,在IPCC国家温室气体清单指南中亦未涉及铝用炭素工业碳排放核算。根据铝用炭素材料具体生产工艺过程中的物料衡算,以物料平衡核算法为主,分别对铝用预焙阳极、铝用石墨化炭阴极生产过程中的碳排放进行了核算,明确了相关核算公式,并选取相关典型数据进行了实际核算。     

Quantitative histologic evaluation of LTI carbon, carbon-coated aluminum oxide and uncoated aluminum oxide dental implants

The response of mandibular bone to identical geometry LTI carbon, carbon-coated aluminum oxide, and uncoated aluminum oxide blade-type dental implants in baboons for 2 years was evaluated using histologic, microradiographic, and scanning electron microscopic methods. In addition, a quantitative histologic analysis was performed identifying the type, amount, and distribution of tissue surrounding the dental implant systems. This is the final phase of a study investigating the effect of implant elastic modulus and implant surface chemical composition on the performance of dental implants. Previous studies have utilized clinical and radiographic evaluations, postretrieval mechanical testing, and finite element stress analysis to evaluate the dental implant performance. The results of the histologic study revealed a direct implant-bone interface with no intervening soft tissue in 16 of the 21 implants (76%). A fibrous tissue interface was observed in 5 of 21 implants (24%). Quantitative histologic results for the implants with a direct implant-bone interface showed statistically larger crestal cortical plates (p less than 0.05) and greater area fraction crestal cancellous bone (p less than 0.05) in the LTI carbon implant compared to the carbon-coated and uncoated aluminum oxide implants. The carbon-coated and uncoated aluminum oxide implants demonstrated statistically greater area fraction cancellous bone at the inferior region of the implant (p less than 0.05) and thinned and reduced crestal cortical plates when compared to the LTI carbon implants. The results indicate that significant stress shielding of the crestal bone had occurred with the rigid carbon-coated and uncoated aluminum oxide implants when compared to the LTI carbon implants which had a material elastic modulus similar to cortical bone. Based upon the histologic results, it appears that the LTI carbon implants with the direct implant-bone interface exhibited a greater potential for long-term successful performance compared to the aluminum oxide substrate implants.