多晶硅真空电磁感应熔炼除磷及其过程研制

磷是多晶硅中的主要杂质元素之一,目前采用的酸洗以及定向凝固工艺无法将其含量降低到太阳能级多晶硅所要求的范围之内。采用自行设计的真空电磁感应熔炼炉及定向凝固炉研究了真空度、精炼时间和精炼温度对除磷效果的影响。研究结果表明当炉内压强为5.0×10-1 Pa时,精炼温度和时间分别为1723K和60min时,精炼后硅中磷含量由原来的2.0×10-5（质量分数）降低到1.8×10-6（质量分数）;研究推导出了在压强为5×10-1Pa下磷的含量随精炼时间和精炼温度的关系式如下：XP=X0Pexp[（-1.43×10-4-3.1×10-7T）t]同时还对真空感应熔炼除磷过程进行了热力学与动力学分析。     

冶金法提纯工业硅的研究

以冶金级硅为原料进行了制备高纯多晶硅锭的研究,自行设计了真空感应熔炼与定向凝固设备、电子束熔炼设备.通过酸洗、真空感应熔炼与第一次定向凝固、电子束熔炼、真空感应熔炼与第二次定向凝固等组合步骤对工业硅进行提纯.利用电感耦合等离子体发射光谱仪(ICP-AES)进行成分分析,实验结果表明,定向凝固有效去除了金属杂质,电子束对蒸汽压高的元素,尤其是磷元素的去除作用明显.Al的浓度降低到了0.4×10~(-6),Fe、Ca、Ti、Mn、Cu、Zn等金属杂质的浓度降到了0.1×10~(-6)以下,P含量降低到1.5×10~(-6).     

定向凝固结合电子束制备高纯铜的研究

对定向凝固结合电子束制备5N高纯铜进行了研究。首先采用真空感应熔炼4N(99.99%)阴极铜并进行定向凝固实验,然后利用电子束对定向凝固后的铸锭进行重熔精炼,利用辉光放电质谱仪进行成分分析。实验结果表明:真空熔炼可以有效去除铜中饱和蒸气压高的杂质;通过定向凝固,杂质元素含量沿铸锭轴向逐渐升高;经过组合工艺提纯后,总杂质含量由13.6×10-6降低至4.0×10-6,铜的纯度提高至99.9996%。     

提纯工业硅除铝的实验研究

为了去除工业硅中的杂质制备太阳能级硅,根据工业硅凝固过程中铝在固相和液相中溶解度的差异,采用定向凝固法去除工业硅中的杂质铝.实验结果表明,铝的去除效率可达98%,说明利用定向凝固法去除工业硅中的铝是可行的.但由于在结晶过程中晶界上会富集部分铝元素,因而定向凝固法并不能除去这一部分杂质.结合金相实验中样品腐蚀前后晶界上的变化,可以知道利用酸浸可以除去晶界上的杂质铝.还研究了先酸浸后定向凝固法相结合除铝,实验结果表明铝的含量可以降到1.6×10-5,铝的去除率达98.6%.     

高纯冶金硅除硼的研究进展

硼是多晶硅太阳电池的受主元素,影响太阳电池的光电转换效率和稳定性.硼在硅中的物理性质很稳定,通过定向凝固、真空熔炼等方法很难去除.主要介绍了冶金法除硼的研究进展,包括吹气造渣除硼、等离子体除硼、合金定向凝固除硼工艺.同时,介绍了本实验室采用冶金法除硼的最新实验结果.     

铸造多晶硅的制备与研究

当今多晶硅已成为最主要的光伏材料,利用定向凝固工艺生产铸造多晶硅铸锭已成为业界广为采用的方法,但目前利用定向凝固工艺生产出来的多晶硅铸锭仍存在较多的缺陷,例如材料利用率低以及组织不均匀等问题.为了进一步优化铸造工艺,采用自行设计的真空电磁感应熔炼炉及定向凝固炉进行了多晶硅定向凝固实验.重点对比研究了石英坩埚和石英陶瓷坩...     

硅系合金法提纯多晶硅的研究进展

硅系合金法近年来已成为冶金法提纯多晶硅的研究热点。大量研究表明,适合的硅系合金能使杂质在硅中的分凝系数大大降低。利用Si-Al合金,通过定向酸洗工艺所得到的多晶硅制成太阳电池其效率最高可达10.6%,在感应磁场下凝固能使Si有效分离,大大降低酸的用量。Si-Ga合金法制成的单晶硅锭,纯度可达5N,太阳能电池的效率也达到了15%,但成本较高。Si-Cu合金则具有容易分离的优点。同时介绍了其他硅系合金的研究进展。     

冶金法制备太阳能级多晶硅的耦合除杂研究

以工业硅为原料,利用介质熔炼、定向凝固和电子束熔炼三种熔体处理技术对工业硅中的B、P和金属杂质进行了去除,制备出了99.9999%级多晶硅材料,其中,杂质B和P的含量分别低于0.20 ppmw（parts per million (weight),百万分之一质量）,金属杂质总含量（TM）低于0.23 ppmw。研究发现,介质熔炼去除杂质B的过程中,熔体中发生氧化还原反应可以有效去除大部分的杂质Al和Ca;电子束熔炼过程中,利用饱和蒸气压原理可以有效去除挥发性杂质P、Al、Ca,同时降束诱导多晶硅定向凝固,可将其他金属杂质进一步去除。本研究通过各技术间的耦合除杂,减少了冶金法提纯多晶硅的工序,为连续化、规模化生产提供了技术支撑。     

低温净化冶金硅工艺探讨

在太阳能级多晶硅生产工艺中,才用冶金净化法去除硼、磷等杂质的方法消耗的能量较大,而金属熔析净化法能够有效的实现冶金硅在金属液环境下低温熔化,然后结晶净化,是一种能耗较低的去除硼、磷的方法。本文主要针对熔析体系选择原则进行分析,对锡、铝等金属作为熔析介质进行筛选,对于Sn-Si体系,在1500K时的硼分凝系数为0.038,小于纯硅熔点0.8。硼的质量分数在冶金硅二次熔析净化处理时可以由15×10-6降至0.1×10-6,一般情况下,其它杂质都可以一次性去除到0.1×10-6以下。在净化的过程中,硅与杂质生成的化合物是去除杂质的主要方法,本文主要针对金属熔析净化法作为基础的低温净化冶金硅的工艺进行分析。     

铁杂质对真空定向凝固多晶硅电阻率的影响研究

利用扫描电子显微镜-X射线能量色散谱、微波光电导衰减法和四探针电阻率测试仪等分析设备,结合Fe-Si二元相图,研究了真空定向凝固多晶硅中Fe杂质的赋存形态和硅锭从底部到顶部四个特征位置径向电阻率的分布情况。结果表明:Fe杂质在真空定向凝固多晶硅中的赋存形态主要为α-Fe(Si)和β-Fe(Si),过饱和固溶体α-Fe(Si)的分解是导致Fe杂质在硅锭中形成沉淀相且浓度分布不均匀的重要原因;Fe杂质在硅锭中不同位置形成的沉淀相与电阻率分布曲线波动相吻合。根据对Fe浓度与电阻率之间的关系以及不同温度下Fe杂质的赋存形态,推导得出了真空定向凝固多晶硅中径向电阻率分布与Fe杂质浓度间的关系式,提出了提高硅锭电阻率均匀性的措施并通过实验得到验证。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...