镁砖在SiO_2-CaO-Al_2O_3熔渣中的侵蚀过程

实验采用经 16 0 0℃ 12ｈ热处理后的商品镁砖。侵蚀试验采用坩埚法 ,渣的主要化学组成 (质量分数 )为 :ＳｉＯ2 4 1% ,ＣａＯ2 4 % ,Ａｌ2 Ｏ3 35 %。为避免熔渣中低熔点玻璃相对镁砖的预先侵蚀 ,将渣置于其他坩埚中先熔化。侵蚀试验的具体步骤如下 :将镁砖坩埚和装渣的铂坩埚     

浸入式水口壁厚对结晶器内钢液速度场和温度场的影响

利用CFD软件计算模拟了浸入式水口壁厚的变化对结晶器内部及液面温度场和速度场的影响.研究表明,壁厚的增加会导致流股的冲击深度增加,涡心高度降低,使钢液的热中心向下移动,同时结晶器水口附近和结晶器1/4处的平均速度约降低了一半,而在结晶器窄边的速度增加了一倍.结晶器下部温度比27.5mm厚水口高2K左右;而在水口附近和1/4处的温度比27.5 mm厚水口低2～3 K,不利于保护渣的熔化,粘结及裂纹率会增加.     

放热型颗粒状结晶器保护渣

为了提高钢质量,必须要改善结晶器保护渣性能,颗粒状结晶器保护渣可以保持良好的工作环境.然而,颗粒状结晶器保护渣保温性能不如粉末状保护渣.为了开发添加金属的放热型颗粒状结晶器保护渣,改善作业环境,开发了添加金属材料的结晶器保护渣新技术,使保护渣有足够热量,并能够改善钢质量.     

氧化钛对含钛不锈钢连铸保护渣性能的影响

针对含钛不锈钢连铸过程结晶器液渣层中TiO2含量明显增加的问题,以配制的含钛保护渣研究了TiO2对不同碱度保护渣的结晶温度、熔化温度、粘度和凝固温度的影响. 结果表明,碱度为0.85时,4.5%的TiO2使渣的结晶温度降低,继续增加TiO2含量,结晶温度不再变化;碱度为1时,随TiO2含量增加,结晶温度先降低后升高,TiO2含量12%时,结晶温度显著升高主要是钙钛矿高温析出造成的. TiO2在0~12%范围增加时,提高了保护渣的熔化温度,降低了保护渣的粘度和凝固温度.     

熔速调节剂对连铸保护渣熔化速度的影响

以石墨、炭黑、碳化硅等3种含碳材料和碱度分别为0.8、1.0和1.2的基渣为原料,研究了三种熔速调节剂炭黑、石墨和碳化硅的加入形式(单独、复合及复合比例)和加入量以及基渣的碱度等因素对保护渣熔化速度的影响,并对试验数据进行了多元线性回归分析。结果表明:1)石墨和炭黑复合加入比单独加入对保护渣熔化速度的影响更明显,尤其当m(炭黑):m(石墨)=1:3时,其作用最明显;2)单独加入碳化硅对保护渣熔化速度的影响不大,但是碳化硅与炭黑以m(SiC):m(炭黑)=1:3的比例复合加入时,保护渣的熔化速度比单独加入炭黑时的小;3)通过对试验数据的多元线性回归分析发现,炭黑在复合调速剂中的质量分数对熔化速度的影响最显著,熔速调节剂的加入量次之,随后依次为石墨在复合调速剂中的质量分数、碳化硅在复合调速剂中的质量分数和渣的碱度。     

隧道窑采取的环保措施

板坯连铸速度的提高导致钢水表面波动和结晶器凝固壳厚度减薄.因此,改进了浸人式水口和结晶器保护渣,以满足连铸条件.新开发的结晶器保护渣"REVIX"系列不仅具有弯月面迅速结晶化缓冷的效果,还确保结晶器下部凝固壳厚度充分传热,实现了高速连铸和抑制铸坯表面裂纹的形成.至于浸入式水口,环状阶梯型浸入式水口和凸型浸入式水口可提供均匀的钢水流和抑制夹杂物侵入结晶器深处.     

高速连铸结晶器保护渣

概述了高速连铸的技术特点及其对结晶器保护渣的要求,论述了高速连铸结晶器用保护渣必须保证的理化性能,总结了高速结晶器保护渣的研究现状,并提出了今后对高速连铸保护渣研制工作的建议。     

连铸结晶器保护渣稳态润滑作用的简化数学分析

根据Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程，并作若干简化假设，建立了描述连铸结晶器内保护渣润滑作用的数学模型．结合凝固规律可以预测结晶器保护渣物理性能和连铸工艺条件对润滑层厚度、保护渣消耗量、拉坯阻力和结晶器内传热的影响．     

添加剂对薄板坯连铸保护渣熔化温度及黏性特征的影响

以工业渣为原料,采用熔体物性综合测定仪等设备,研究了添加剂Li2CO3、NaF、Na2CO3、冰晶石及硼砂对薄板坯连铸保护渣熔化温度、黏度及流动性的影响。结果表明:加入Li2CO3能显著降低保护渣的熔化温度和黏度,增加流动长度。NaF加入质量分数为10%~20%时,保护渣的熔化温度下降较快,黏度下降缓慢,流动长度增加。加入Na2CO3对保护渣的熔化温度、黏度和流动长度影响不大。冰晶石加入质量分数为5%~15%时,保护渣的熔化温度和黏度降低,流动长度增加;冰晶石加入质量分数为15%~20%时,保护渣的熔化温度增加。硼砂加入质量分数在2%~6%时,保护渣的熔化温度降低,黏度平缓降低,流动长度增加;硼砂加入质量分数超过6%后,保护渣的黏度略有增加。     

电解锰压滤渣高温脱硫研究

采用直接煅烧法、还原法及添加脱硫剂煅烧法对电解锰压滤渣进行了高温脱硫,研究了不同方法得到的脱硫产物的物相、残硫量和活性,并比较了几种方法的工业适用性。结果表明:直接煅烧法的脱硫渣和坩埚粘连严重,实际操作困难;加入煤粉并没有改善脱硫渣和坩埚的粘连问题,且脱硫渣中残硫量高;石灰石虽能减弱脱硫渣和坩埚的粘连,但由于生成惰性物质石英,降低了脱硫渣的活性;采用铝矾土作为脱硫剂进行脱硫,脱硫渣的残硫量低,脱硫渣和坩埚不粘连,脱硫渣活性高。铝矾土添加量为42%(质量分数),脱硫温度为1 250 ℃,脱硫保温时间为5 min时,脱硫渣中硫含量为0.089 4%(质量分数),达到脱硫要求。     

A novel potential ceramic material for melting Ti6Al4V alloy: A solid solution of BaZrO3 and CaZrO3

Vacuum induction melting technology is a promising low-cost method for producing high-quality titanium alloy. The key challenge lies in the development of ceramic crucibles with excellent chemical stability for titanium alloy corrosion. In this work, (Ba_1−x,Ca_x)ZrO₃ ceramic was designed and synthesised via pressureless sintering of a mixture of BaZrO₃ and CaZrO₃ powders. X-ray diffraction and scanning electron microscopy analyses showed that a new phase, Ba_0.8Ca_0.2ZrO₃, was formed after heat treatment at 1700 °C. Vacuum induction melting experiments of the Ti6Al4V alloy were carried out using a Ba_0.8Ca_0.2ZrO₃ crucible. Compared with the original BaZrO₃ crucible and CaZrO₃ crucible, the erosion layer of the Ba_0.8Ca_0.2ZrO₃ crucible was significantly reduced by approximately 85∼92.5%. The interface between the crucible and the alloy was clearly visible, and there was no obvious element diffusion between the alloy and the material. This shows that Ba_0.8Ca_0.2ZrO₃ is highly promising as a crucible material for melting Ti6Al4V alloys.     

Obtaining high-purity fused refractory oxides

Conclusions Using yttrium oxide and aluminum oxide as examples we demonstrated the possibility of successfully using the induction heating method in a cold crucible for obtaining fused refractory materials possessing a high purity. The contamination of the charge by the crucible material during melting does not exceed 10^–3%.Translated from Ogneupory, No. 7, pp. 26–29, July, 1973.     

Quartzites for crucibles and methods of lining crucible induction furnaces (Review)

Conclusions With observation of the requirements of chemical and grain-size compositions, progressive methods of lining work, and sintering of the crucible, domestic quartzites provide a long lining life of induction crucible furnaces in melting of iron and sufficient life in melting of carbon steel.Translated from Ogneupory, No. 6, pp. 48–52, June, 1985.     

Interaction between CA6-MA crucible and molten wrought Ni-based superalloys

The interfacial behavior between CaAl₁₂O₁₉-MgAl₂O₄ spinel (CA₆-MA) crucible and molten wrought Ni-based superalloys during the vacuum induction melting process have been comprehensively investigated, with Al₂O₃ crucible included for comparison. Experimental and theoretical results suggest that CA₆-MA crucible exhibits higher thermodynamic stability and poor wettability to the superalloy melt. Benefited from these merits, the superalloy ingot with cleaner surfaces and more metallic luster is obtained in the CA₆-MA crucible. Furthermore, the total oxygen content in the superalloy ingots obtained from CA₆-MA crucible is 17.9 ppm, which is considerably lower than that from Al₂O₃ crucible (29.7 ppm). These results indicate that CA₆-MA crucible can be a promising candidate for melting wrought Ni-based superalloys.     

Oxidation–Reduction Equilibrium in Copper Phosphate Glass Melted in Air

Copper phosphate glasses with 40, 50, and 60 mol% CuO in batch were melted in air at 1000°, 1100°, and 1200°C using quartz or alumina crucibles, and the [Cu²⁺]/[Cu_total] ratio variations with melting time were measured. Glasses were oxidized during melting and reached equilibrium [Cu²⁺]/[Cu_total] ratios which were independent of melting temperature and identical for the 40 and 50 mol% CuO content glasses. Structural considerations seemed to have determined oxidation-reduction equilibrium rather than an equilibrium redox reaction. Also, the effects of crucible type on the oxidation-reduction balance were examined. It was found that a quartz crucible is more inert and has less effect on the oxidation-reduction equilibrium of glass than an alumina crucible. Crucible contamination and phosphorus vaporization were found to diminish as the CuO content in the batch was increased.     

CaZrO_3耐火材料的制备及其与钛合金熔体的界面反应

合成了一种CaO-ZrO_2系复合耐火材料,用模压法成型,分别在1 650℃和1 680℃烧结制成坩埚.使用此坩埚在感应炉中熔化钛合金(TiNi),在真空条件下, 1 500℃保温5min.对在1 680℃烧结成的坩埚进行了抗水化性能测试.用X射线衍射仪对CaZrO_3材料进行物相分析.用扫描电子显微镜观察钛合金与此材料的界面反应层的微观形貌,结合能谱仪进行微区成分分析.结果显示:1 680℃烧成的CaZrO_3材料具有良好的抗水化性;用此坩埚熔化TiNi合金后,液态钛合金和耐火材料的界面反应层厚度约为30μm,界面反应层中,Ca,Zr,Ti,Ni等元素无明显扩散.     

INFLUENCE OF BATCH MIXING TIME AND BATCH GRAIN SIZE ON HOMOGENEITY OF A SODA-LIME-SILICA GLASS*

Density-spread determinations were made on a series of melts of a soda-lime-silica glass employing batches compounded from raw materials varying in particle size from 20- to 60-mesh to minus 200-mesh, which had been mixed by tumbling for one, ten, or thirty minutes. The two melting techniques employed were (1) melting for sixteen hours in a stationary platinum crucible at 1400°C. under conditions of even temperature distribution and consequently a minimum of convection mixing and (2) melting for four hours at 1400°C. in a rotating tilted crucible; this condition was intended to simulate convection mixing Under the experimental conditions employed, it was found that (1) batch mixing time has relatively little effect on the homogenizing rate, (2) homogenization increases rapidly with decrease in grain size, and (3) in all cases the 4-hour melting treatment with moderate mixing gives better homogeneity than sixteen hours melting time in a stationary crucible, this effect increasing with decrease in grain size. No significant difference in glass homogeneity resulted from three different methods of mixing, namely, tumbling, ball milling, and mixing in a muller-type mixer, although the homogenizing influence imposed probably was sufficient to mask any differences in uniformity of mixing that might have existed.     

X-ray imaging of a high-temperature furnace applied to glass melting

The dynamics of soda-lime-silica glass grain melting is investigated experimentally using a nonintrusive technique. A cylindrical alumina crucible is filled with glass cullet and placed into a furnace illuminated by an X-ray source. This glass granular bed is gradually heated up to 1100°C, leading to its melting and the generation of a size-distributed population of bubbles rising in the molten glass. An image processing algorithm of X-ray images of the cullet bed during melting allows the characterization of bubbles size distribution in the crucible as well as their velocity. The introduction of tin dioxide μ-particles in the glass matrix before melting enhances the texture of the images and makes possible the determination of the bubble-induced molten glass velocity field by an optical flow technique. The bubble size distribution can be fitted by a log-normal law, suggesting that it is closely related to the initial size distribution in the cullet bed. The liquid motion induced by the bubbles in Stokes' regime is strongly affected by the flow confinement and the determination of bubble rising velocity along its trajectory unveils the existence of local tiny temperature fluctuations in the crucible. Overall, the measuring techniques developed in this work seem to be very promising for the improvement of models and optimization of industrial glass furnaces.     

BaZrO3 refractory crucibles for vacuum induction melting of industrial Zr-based bulk metallic glass master alloys with Y addition

The absence of appropriate melting method and expensive cost of high-purity Zr raw material limit the commercial application of Zr-based bulk metallic glass. In the present study, using high oxygen industrial grade sponge Zr as raw material and the metal Y as additive, the low-cost and high-purity master alloys were successively prepared using a VIM method with a BaZrO₃ refractory crucible. The results indicate that the BaZrO₃ refractory exhibited good erosion resistance to the alloy melt, the Y additive formed the Y₂O₃ barrier layer on the surface of crucible, which prevented the melt permeation into the crucible, then effectively reduced the thickness of the erosion layer. In addition, the metal Y deoxidizer could remove the oxygen of melts, finally the low oxygen Zr-based master alloy (about 0.02 wt%) was prepared. These results may provide a promising preparing technique prototype of low-cost Zr-based bulk metallic glass.     

浅析煤质分析高温炉升温速度的控制方法

根据实验室常用的一些高温炉常具有热惯性（即时间滞后性）而对控温精度不高的缺陷提出了“加速度超前控制法”的原理并设计制造出了具有控温精度、适用于灰熔点炉、葛全试验炉和坩埚膨胀序数测定炉等高温炉的控温仪器。