热轧不锈钢复合板冲击性能研究

研究在不同复合比及温度条件下冲击载荷对热轧不锈钢复合板力学性能的影响。结果表明,热轧复合板随覆层厚度增大或试验温度升高,其冲击吸收能增大,覆层厚度为8mm时,冲击功达到稳定值150J;碳钢层断面为解理面与韧窝混合断裂形貌,不锈钢层断面为韧窝断裂形貌,靠近复合界面不锈钢侧呈沿晶断裂与韧性断裂形貌;复合界面处开裂情况对缺口位置不敏感;热轧不锈钢复合板冲击加载过程复合界面不易开裂。     

钢铁表面Cu—Sn—P／Ni—Sn—P合金复合镀层的结构和性能

钢铁表面浸镀Cu-Sn-P合金，得到金黄色仿金镀层．在金黄色镀层上化学镀法Ni—Sn—P合金，形成Cu-Sn-P／Ni-Sn-P合金复合镀层，确定了镀液的最佳组成和工艺，用盐水浸泡测定复合镀层的防腐蚀性，用SEM，XPS和AES谱分析镀层的表面形貌、组成、结构和性能．结果表明，合金复合镀层使钢铁耐腐蚀性得以改善，Cu—Sn—P镀层可表示为Cu—Sn—P／CuxOy／SnxOy；Ni—Sn—P镀层可表示为Ni—Sn—P／NixOy／SnxOy，各元素的相对原子百分浓度分别为Ni52．2％，O6．9％，Sn18．7％，P12．9％，Fe9．3％．     

离心铸造碳钢-高铬铸铁复合管有限元模拟研究

采用离心铸造的碳钢--高铬铸铁复合管界面达到了冶金结合.利用ANSYS有限元软件对复合管凝固过程外层及内外层温度场进行了模拟与分析.模拟结果表明:离心浇注外层20钢大约9 s后,铸件最低温度为1430℃,已经低于20钢固相线温度1490℃,由此可见,浇注间隔时间为9s时,可形成规则稳定的过渡层.当外层20钢的温度降至1350℃时,浇注高铬铸铁,大约30 s后,内层的温度已降至1257℃,低于高铬铸铁固相线温度,此时,内层熔体已经完全凝固.     

镍含量对激光熔覆层微结构及硬度的影响

为满足多种支承辊再制造表面硬度需求,采用激光熔覆技术,将添加不同比例纯镍粉的铁基合金粉末材料熔覆到Cr5支承辊钢表面,研究镍含量对熔覆层微结构及性能的影响.结果表明:所有材料设计成分条件下熔覆层的截面组织差异很小均为鱼骨状和网状枝晶组织.通过调整添加镍粉的量可以准确控制熔覆层的合金成分.随熔覆层中镍含量增多,熔覆层中奥氏体相显著增多,截面硬度显著下降.添加8%纯镍粉的粉末材料可以制备出硬度约为500 HV,可以满足Cr5支承辊再制造需求.     

表面处理方式对钛/钢复合板界面结合性能的影响

采用真空制坯轧制复合法,在相同的加热温度、轧制道次和压下量等工艺条件下,分别对钢丝刷打磨、酸洗和带水砂带机打磨的表面处理方式,研究了3组钛/钢复合板的界面组织和力学性能.分析了表面处理方式对界面结合性能的影响.结果表明:带水砂带机表面处理方式下的钛/钢复合界面生成连续均匀的TiC层,剪切断口呈韧窝状,界面剪切强度稳定,平均强度达到242.6MPa.其他两种表面处理方式下的钛/钢复合板界面生成断续的TiC层,其剪切强度均未满足国家标准.     

Dripping and evolution behavior of primary slag bearing TiO<Subscript>2</Subscript> through the coke packed bed in a blast-furnace hearth

To investigate the flow of primary slag bearing TiO₂ in the cohesive zone of blast furnaces,experiments were carried out based on the laboratory-scale packed bed systems.It is concluded that the initial temperature of slag dripping increases with decreasing FeO content and increasing TiO₂ content.The slag holdup decreases when the FeO content is in the range of 5wt%-10wt%,whereas it increases when the FeO content exceeds 10wt%.Meanwhile,the slag holdup decreases when the TiO₂ content increases from 5wt% to 10wt% but increases when the TiO₂ content exceeds 10wt%.Moreover,slag/coke interface analysis shows that the reaction between FeO and TiO₂ occurs between the slag and the coke.The slag/coke interface is divided into three layers:slag layer,iron-rich layer,and coke layer.TiO₂ in the slag is reduced by carbon,and the generated Ti diffuses into iron.     

Fabrication of plain carbon steel/high chromium white cast iron bimetal by a liquid–solid composite casting process

High-chromium white cast iron(HCWCI) is one of the most widely used engineering materials in the mining and cement industries. However, in some components, such as the pulverizer plates of ash mills, the poor machinability of HCWCI creates difficulties. The bimetal casting technique is a suitable method for improving the machinability of HCWCI by joining an easily machined layer of plain carbon steel(PCS) to its hard part. In this study, the possibility of PCS/HCWCI bimetal casting was investigated using sand casting. The investigation was conducted by optical and electron microscopy and non-destructive, impact toughness, and tensile tests. The hardness and chemical composition profiles on both sides of the interface were plotted in this study. The results indicated that a conventional and low-cost casting technique could be a reliable method for producing PCS/HCWCI bimetal. The interfacial microstructure comprised two distinct layers: a very fine, partially spheroidized pearlite layer and a coarse full pearlite layer. Moreover, characterization of the microstructure revealed that the interface was free of defects.     

铜钢复合材料覆层金属锌含量的测定

研究了不同比例过硫酸铵氨水溶液溶解铜钢复合材料覆层金属的试验方法,确定用33 g过硫酸铵溶入500 mL氨水（1：1）中的覆层溶解液可以均匀溶解覆层金属,并对基体没有影响的试验方法.在覆层金属溶解后的液体中,pH为5~6时,以氟化钾、抗坏血酸掩蔽铁及其他杂质,以硫脲掩蔽铜,二甲酚橙为指示剂,乙二胺四乙酸二钠（EDTA-2Na）标准溶液滴定锌,滴定终点明显,效果较好.用该方法对铜钢复合材料进行精密度试验,RSD（n=11）在0.83%~1.58%,加标回收试验,加标回收率在97%~101%.建立了铜钢复合材料覆层金属锌含量测定的新方法,该方法操作简便,精密度高.     

钢基底上预镀中间层沉积金刚石膜

利用表面预镀中间层在４５号钢上化学气相沉积（ＣＶＤ）得到了金刚石膜。钢基底表面金刚石涂层具有许多潜在应用价值，但直接在钢上沉积生长金刚石面临长的形核期，铁原子的触媒作用和热膨胀不匹配等严重问题。文中采用钢基底表面预镀中间层的方法，阻止碳向基底中扩散，增强膜基结合和抑制ＳＰ２杂化碳的沉积。分别研究了直接在钢基底上、表面预镀铜膜和表面预镀硅膜钢基底上热丝法沉积金刚石膜的工艺特点。通过ＳＥＭ、Ｒａｍａｎ谱和划痕法检验表明，钢基底表面预镀硅膜作为中间层，是一种在钢上沉积金刚石膜的有效方法。     

模具钢表面激光涂覆硬面合金层的研究

本文应用１．５ｋＷ横流式ＣＯ２气体激光器将ＮｉＷＣ２５，Ｎｉ５５，Ｆｅ４５０，ｓｔｅｌｉｔｅ１２等四种硬面合金粉末涂覆在Ｙ４模具钢的表面，用扫描电镜能谱仪、光学显微镜、Ｘ射线衍射仪、显微硬度计、耐磨实验机等分别对合金层的剖面元素分布、合金层的微观组织、相组成、显微硬度及耐磨性等进行了较详细的测定分析．研究结果表明：合金涂覆层与基材在激光作用下能形成良好的冶金结合；合金层的组织是以过饱和奥氏体基相上弥散分布着碳化物和硼化物的多元共晶组织；该合金层具有优于Ｙ４模具钢的耐磨性能，其中以ＮｉＷＣ２５合金层的耐磨性最优异．     

利用超重力富集和分离Sn-3％Fe熔体中的杂质元素铁

在粗锡精炼过程中引入超重力场,运用超重力技术研究Sn-3％Fe(质量分数)熔体中杂质元素铁在超重力场中的定向富集和过滤分离的规律,达到提纯净化粗锡的目的.结果表明,对于超重力场G=500以10℃·min-1冷却速率凝固后的Sn-3％Fe熔体,超重力场极大强化富铁相在粗锡熔体中的沉降运动,使先析出富铁相全部富集到试样的下部区域,上部几乎找不到富铁相颗粒.下部尾锡中的铁质量分数达到4.817％,而上部精锡中的铁质量分数降低到0.036％,精锡中铁的脱除率高达98.78％.在超重力场中过滤的Sn-3％Fe熔体可实现富铁相杂质和精锡液的有效分离,当重力系数大于30时,精锡的回收率随重力系数的增大而提高.在超重力场G=100,240℃条件下,Sn-3％Fe熔体过滤1 min后,精锡液几乎全部被分离到坩埚底部,富铁相杂质被截留在过滤碳毡上部,下部精锡中找不到富铁相杂质的颗粒,精锡中铁质量分数降至0.253％,富铁渣中铁质量分数高达11.528％.精锡中铁的脱除率高达91.44％,超重力场中精锡的回收率高达82.69％.     

CFRP约束圆钢管高强混凝土短柱轴压试验研究

为研究混凝土强度、径厚比、CFRP(碳纤维增强复合材料)层数及CFRP包裹方式等参数对CFRP约束圆钢管混凝土轴压静力性能的影响,进行了6个圆钢管混凝土短柱和18个CFRP-钢管混凝土短柱的轴压对比试验.研究发现CFRP的约束对圆钢管混凝土承载力有较显著的提升,且承载力的提高幅度随着CFRP的增加而增加.钢管高强、超高强混凝土短柱的破坏形态呈现为剪切破坏,延性较差,CFRP的约束可以改善其延性,且CFRP层数越多延性越好.半包CFRP试件性能接近于全包CFRP试件性能.随径厚比增大,CFRP约束效果下降.若黏结良好,试件失效前,CFRP与钢管能保持协同工作;最后选取了3个经典的CFRP约束钢管混凝土轴压承载力公式进行验算,发现基于CFRP和钢管双重约束的公式能较好地预测其承载力.     

工具钢表面激光熔覆耐磨性试验研究

使用5kWCO2激光器对9SiCr工具钢表面进行Co基和Ni基合金熔覆处理·利用销盘式摩擦试验机对激光熔覆表面和Q235配副进行干摩擦和油润滑试验,通过扫描电镜研究了熔覆层表面磨损形貌并分析了干摩擦和润滑条件下磨损机理·试验结果表明,熔覆区磨损形式主要是磨粒、粘着磨损·干摩擦时,Ni合金熔覆层比Co合金耐磨性要好;润滑条件下,两种合金的耐磨性比干摩擦时都有很大提高     

真空轧制不锈钢复合板的组织和性能

采用真空轧制法对6mm厚的奥氏体不锈钢板和50mm厚的碳钢板复合.在高真空、高温和大轧制力的共同作用下,界面实现了牢固的冶金结合并且最终得到了高质量的不锈钢复合板.研究发现界面无开裂和氧化层,仅在界面附近分布少量细小弥散的Si-Mn氧化物颗粒.通过能谱发现不锈钢侧的Cr和Ni向碳钢迁移,在界面形成一薄层富Cr,Ni层,导致复合层硬度升高;碳钢中的C向不锈钢侧迁移导致出现脱碳区,且该区硬度最低.界面的剪切强度达467MPa.     

Deposition of 1.88-billion-year-old iron formations as a consequence of rapid crustal growth

Iron formations are chemical sedimentary rocks comprising layers of iron-rich and silica-rich minerals whose deposition requires anoxic and iron-rich (ferruginous) sea water. Their demise after the rise in atmospheric oxygen by 2.32?billion years (Gyr) ago has been attributed to the removal of dissolved iron through progressive oxidation or sulphidation of the deep ocean. Therefore, a sudden return of voluminous iron formations nearly 500?million years later poses an apparent conundrum. Most late Palaeoproterozoic iron formations are about 1.88?Gyr old and occur in the Superior region of North America. Major iron formations are also preserved in Australia, but these were apparently deposited after the transition to a sulphidic ocean at 1.84?Gyr ago that should have terminated iron formation deposition, implying that they reflect local marine conditions. Here we date zircons in tuff layers to show that iron formations in the Frere Formation of Western Australia are about 1.88?Gyr old, indicating that the deposition of iron formations from two disparate cratons was coeval and probably reflects global ocean chemistry. The sudden reappearance of major iron formations at 1.88?Gyr ago--contemporaneous with peaks in global mafic-ultramafic magmatism, juvenile continental and oceanic crust formation, mantle depletion and volcanogenic massive sulphide formation--suggests deposition of iron formations as a consequence of major mantle activity and rapid crustal growth. Our findings support the idea that enhanced submarine volcanism and hydrothermal activity linked to a peak in mantle melting released large volumes of ferrous iron and other reductants that overwhelmed the sulphate and oxygen reservoirs of the ocean, decoupling atmospheric and seawater redox states, and causing the return of widespread ferruginous conditions. Iron formations formed on clastic-starved coastal shelves where dissolved iron upwelled and mixed with oxygenated surface water. The disappearance of iron formations after this event may reflect waning mafic-ultramafic magmatism and a diminished flux of hydrothermal iron relative to seawater oxidants.     

TiC/Fe cermet coating by plasma cladding using asphalt as a carbonaceous precursor

A new Ti-Fe-C compound powder for plasma cladding was prepared by heating a mixture powder of ferrotitanium and asphalt pyro-lyzed as a carbonaceous precursor. The carbon by the pyrolysis of the asphalt acts as a reactive constituent as well as a binder in the compound powder. The TiC/Fe cermet coatings were prepared by plasma cladding with the compound powder. Results show that the Ti-Fe-C compound powder has a very tight structure, which can avoid the problem of the reactive constituent particles being separated during cladding. The TiC/Fe cermet coating presents a typical morphology of plasma cladding coatings with two different laminated layers: one is the composite layer in which the round fine TiC particles (<500 nm) are dispersed within a Fe matrix, the other is the paragentic layer of TiC and Ti2O3. The coating shows high hardness and excellent wear resistance. The surface hardness of the coating is 68 ± 5(HR30N). In the same fretting conditions, the wear area of Ni60 coating is about 11 times as much as the TiC/Fe cermet coating.     

铜/钢/铜冷轧复合薄带弯曲性能实验研究

以Q345钢带为基材，T3纯铜为覆材，通过冷轧复合—中间退火—冷轧减薄—轧后退火的工艺路线，制备出铜/钢/铜复合薄带.通过反复弯曲实验研究复合带厚度和退火温度对复合带弯曲性能的影响.实验发现:复合带的弯曲性能主要依赖于冷轧复合中的机械作用以及退火过程中的扩散作用.冷轧复合带随着厚度逐渐减薄，弯曲性能近似线性增强.退火工艺能大幅度提高复合带的弯曲性能，退火温度与弯曲性能基本呈指数关系变化.     

反向凝固1Cr18Ni915F复合铸带微观组织特征和界面剪切强度

采用反向凝固法在实验室条件下研究奥氏体不锈钢复合带制取的工艺过程,通过对 复合铸带试样的金相和扫描电镜研究,发现了复合铸带由具有不同微观组织特征的３个区域 组成,即碳素钢母带区、不锈钢新相层和界面过渡区．复合铸带界面剪切强度试验的结果表明, 反向凝固奥氏体不锈钢复合铸带的界面结合性能完全达到国标的要求．     

激光熔覆对38CrMoAl钢表面改性

研究了利用横流ＣＯ２激光器在３８ＣｒＭｏＡｌ表面激光器熔覆ＮｉＣｒＢＳｉ＋ＷＣ（２５％ｗｔ）复合合金层的组织、硬度与耐磨性。用扫描电镜观察组织形貌,用Ｘ射线仪进行物相分析,用摩擦磨损试验机进行耐磨性实验：合金层与基体成良好的无裂纹气孔的冶金。表面耐磨性与工艺参数具有一定的对应关系,且２．２ｋＷ时的耐磨性最高,为氮化工艺的７．８倍。     

钎焊-热轧法制备高速公路不锈钢复合护栏

针对当前高速公路热镀锌护栏存在的主要问题,提出采用不锈钢/碳钢复合板作为新型高速公路护栏材料.研究了钎焊-热轧法制备不锈钢复合护栏的工艺,技术路线为通过炉中钎焊实现不锈钢/碳钢的初结合,对钎焊复合板进行热轧进一步提高结合强度.研究结果表明:采用自制的Ag质量分数为15%的钎料可以实现不锈钢/碳钢有效的钎焊结合,钎焊温度720~730℃,钎焊时间3~4 min是较理想的工艺条件.对钎焊复合板热轧可以显著提高不锈钢/钎料界面的结合强度,压下率低于30%时,轧后钎料层未出现断裂、分层.热轧后,不锈钢复合护栏剪切强度可达338.4 MPa.