首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 46 毫秒
1.
交变电磁场下金属熔体的电磁约束连续成形与凝固   总被引:6,自引:3,他引:3  
论述了连续铸造中模壳材料对铸件性能的影响。在介绍液态金属电磁成形原理的基础上,重点讨论了铝合金和钢铁材料的电磁成形以及存在的问题,并提出了液态金属电磁近终成形技术。利用开发的双频电磁近终成形技术,成功地实现了两种不同频率组合下的电磁成形过程,制备出了复杂弯月截面、复杂形状无模壳电磁成形的样件。  相似文献   

2.
对液态金属双频电磁成形中三种圆形截面感应圈配置形式中磁感应强度分布进行了计算 ,结果发现 :(1 )直筒和直筒感应圈组合形式中磁感应强度和电磁压力在轴向上易造成两个峰值分布 ,而斜筒和直筒 ,斜筒和斜筒感应圈组合形式可得到与液态金属静压力分布趋势相同的磁感应强度和电磁压力分布 ;(2 )在径向上 ,离双感应圈内壁越近 ,三种配置形式感应圈产生的磁感应强度和电磁压力越大 ,液态金属双频电磁成形形状的稳定性也就越高 .  相似文献   

3.
金属熔体电磁成形过程研究   总被引:1,自引:0,他引:1  
以制备无污染的航空发动机叶片为背景 ,分析了金属熔体电磁成形定向凝固技术的原理 ,并以铝合金及 1Cr1 8Ni9Ti为研究材料 ,探讨了交流电磁场作用下金属熔体的感应加热熔化及约束成形过程 ,结果表明 :感应器结构决定其内部的磁场及电磁压力分布 ,感应器输入功率、熔体高度、上下液固界面位置、抽拉速度及冷却条件等参数综合影响金属加热熔化特性、熔体形状及其稳定性 ;通过控制合理的工艺参数 ,获得了截面为圆形及近似弯月面形、表面质量和内部定向组织良好的样件 .  相似文献   

4.
为解决由机械振动产生的超声波无法在高温环境中成功应用的难题,提出了利用静磁场和交流电流、静磁场和交流磁场的相互作用分别在金属液内直接生成高强度电磁超声波的方法,运用超声波压力传感器对用这两种方法在金属液内生成的电磁超声波的强度进行了测量。研究表明:电磁超声波的强度与所施加的高频电磁力的强度成正比,频率与电磁力的频率相同;实验结果和理论解析结果基本一致;利用高频电磁力的局部作用在金属液全场范围内生成的电磁超声波可以在金属精炼及凝固过程中获得广泛应用。  相似文献   

5.
金属熔体的电磁成形与凝固   总被引:18,自引:0,他引:18  
材料的电磁加工是当今材料加工技术领域研究和发展的一个重点。本文简述作为材料电磁加工技术理论基础的电磁流体力学的基本内容,给出电磁场各种的基本原理,着重阐述电磁力和焦耳热在金属熔体电磁成形与凝固过程中的应用。  相似文献   

6.
高温合金电磁软接触近净成形定向凝固研究   总被引:6,自引:2,他引:4  
传统高温合金叶片类铸件制备过程中,熔体长时间受到陶瓷模壳材料的污染,性能难以提高,借助于电磁软接触成形技术中的电磁压力使高温合金熔体呈半悬浮状态,减少了熔体与磁模结晶器的接触面积和时间,提高了合金熔炼和成形的纯净度,同时将该技术和定向凝固技术相结合开发了一种实现高温合金复杂形状电磁软接触成形定向凝固的工艺,并探讨了该工艺下3种结晶器材料(陶瓷、磁模和石墨)中磁感应强度的分布规律,结果表明,石墨套高度对磁模结晶器磁感应强度的大小和分布以及熔体温度场有很大影响。通过调整上下线圈功率和抽拉速度等工艺参数成功地制备了大小两种近叶片形状的高温合金电磁软接触成形的定向凝固样件。.  相似文献   

7.
中小尺寸高温合金件的无接触电磁成形   总被引:7,自引:1,他引:6  
介绍了一种新型金属熔体无接触电磁成形技术及其原理,该技术将电磁铸造技术与高梯度定向凝固技术融为一体,对于熔化和成形活泼金属、高温合金难熔金属和高纯金属等中小尺寸构件具有重要的研究与应用价值。另外,从电磁场和凝固过程角度讨论了中小尺寸高温合金样件的电磁成形过程,探讨了工艺参数对成形过程的影响规律,并获得了表面质量较好的高温合金样法。  相似文献   

8.
电磁成形是一种典型的高速率成形技术,能显著提高材料的成形性能,并已经成功应用于金属板材成形领域,获得了很好的成形效果.为了能够继续扩大电磁成形技术在板材成形方面的应用,对目前板材电磁成形技术研究进展进行了综述.首先介绍了电磁成形工艺的原理与主要特点;分析了目前电磁成形技术、电磁辅助冲压成形技术在金属板材成形方面的研究进展;提出了电磁成形技术在应用研究方面存在的主要问题,并展望了该技术的发展趋势;最后,分别从成形材料和成形工艺两个方面分析了后续研究的突破点以实现扩大该技术应用的目的.  相似文献   

9.
合金电磁约束成形及凝固组织控制研究   总被引:3,自引:0,他引:3  
介绍了铁、镍基合金等的无接触电磁约束成形定向凝固技术。在系统研究电磁场与温度场及其耦合作用的基础上,成功地实现了对多种截面形状的铝、不锈钢及高温合金的无容器电磁约束成形。  相似文献   

10.
旋转电磁场作用下金属凝固补缩机理探讨   总被引:1,自引:0,他引:1  
研究了金属熔体在旋转电磁场作用下的凝固过程。据金属凝固理论和磁流体力学分析,电磁搅拌力引起的动量对流对补缩的促进作用并不大。旋转电磁场阻碍中心疏松、缩孔形成的机制为:电磁力引起的动量对流增强了熔体的热、质传输过程,使熔体温度分布更趋均匀,温度梯度减小,使心部熔体的固相率更趋一致且在短时内增至特征固相分数,且凝固末期熔体的凝固速率增大,使心部熔体在短时内凝固,从而避免了中心疏松、缩孔的形成。  相似文献   

11.
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.  相似文献   

12.
13.
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.  相似文献   

14.
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……  相似文献   

15.
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.……  相似文献   

16.
A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.  相似文献   

17.
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.  相似文献   

18.
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 ...  相似文献   

19.
Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.  相似文献   

20.
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...  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号