Sintering characteristics of low-rank coal ashes

The electrical resistance and compressive strength were measured to gain a better understanding of the sintering characteristics of low-rank coal ashes involved in deposit formation in combustion systems. Low-rank coal ashes were prepared by the standard ASTM ashing procedures at 750°C and then separated into three different particle size fractions. The sinter point determined by the electrical resistance method decreased with decreasing particle size at three different particle size fractions of each coal ash. The compressive strength lest was made as a function of temperature in the range 750–950°C. At a given sintering temperature, strength of the sintered ash was inversely proportional to particle size. For any given particle size of each coal ash, the strength increased with increasing sintering temperature. X-ray diffraction of the sintered coal ashes showed that, as sintering temperature increased, there was an inverse relationship between sinter strength and the amount of anhydrite in the sintered ash, and a direct relationship between strength and the amount of hauyne.     

Review of suspension and solution precursor plasma sprayed thermal barrier coatings

As one of the promising methods that can be employed to fabricate high-performance thermal barrier coatings (TBCs), suspension plasma spraying (SPS) or solution precursor plasma spraying (SPPS) has received significant attention in academic research. Enhanced performances have been shown in the SPS-/SPPS-coatings due to their special microstructures, such as uniformly distributed micro-pores, vertical cracks or columnar structures. Since there are more complexities than conventional plasma spraying methods, many works have been devoted to study the mechanism and properties of SPS-/SPPS-coatings during the past decades. In this work, the latest development of SPS or SPPS is reviewed in order to discuss some key issues in terms of preparation of suspension or solution precursor, injection mode of liquid phase, interaction between liquid and plasma jet, microstructure of as-sprayed coatings and corresponding deposition mechanism. Meanwhile, the potential application of SPS or SPPS in some new-type TBCs is introduced at the end of this paper.     

Influence of Stratification and Shoreline Erosion on Reservoir Sedimentation Patterns

Sedimentation in the main pool of a deep (maximum depth: 50?m), 227?km2 hydropower reservoir was modeled using a three-dimensional numerical model of hydrodynamics and sedimentation for different wind, inflow, and outflow conditions. Short-term velocity measurements made in the reservoir were used to validate some aspects of the hydrodynamic model. The effects of thermal stratification on sedimentation patterns were investigated, since the reservoir is periodically strongly stratified. Stratification alters velocity profiles and thus affects sedimentation in the reservoir. Sedimentation of reservoirs is often modeled considering only the deposition of sediments delivered by tributaries. However, the sediments eroding from the shorelines can contribute significantly to sedimentation if the shorelines of the reservoir erode at sufficiently high rates or if sediment delivery via tributary inflow is small. Thus, shoreline erosion rates for a reservoir were quantified based on measured fetch, parameterized beach profile shape, and measured wind vectors, and the eroded sediments treated as a source within the sedimentation modeling scheme. The methodology for the prediction of shoreline erosion was calibrated and validated using digital aerial photos of the reservoir taken in different years and indicated approximately 1?m/year of shoreline retreat for several locations. This study revealed likely zones of sediment deposition in a thermally stratified reservoir and presented a methodology for integration of shoreline erosion into sedimentation studies that can be used in any reservoir.     

压电陶瓷表面化学镀Ni-W-P合金工艺研究

研究了镀液各组分和工艺条件对沉积速率、结合强度等的影响,并研究了镀层耐海水腐蚀性能和镀液稳定性,最终确定了合适的压电陶瓷化学镀Ni-W-P合金配方。     

吐哈油田生产井蜡沉积物系统分析及蜡沉积机理探讨

用溶剂萃取分离，气相色谱，红外光谱、核磁共振等方法分析研究了吐哈油田特别是鄯善油田生产井的蜡沉积物，吐哈原油中的蜡按烷烃碳数分布有Ｃ１３－Ｃ３５和Ｃ３０－Ｃ６５两个峰区，其中第二峰区的高碳石蜡含量超过蜡总含量的５０％，蜡熔点很高，为８４－１００℃，基本上是不带支链的纯粹正构烷烃，极易从原油中析出。对蜡沉积作了初步探讨和推论。     

140 GHz兆瓦级回旋管高斯模式输出窗设计

根据热核聚变用140 GHz回旋振荡管研制需要,对高斯模式输出窗进行研究。以化学气相沉积金刚石作为输出窗片的材料,通过理论分析,优化设计出低反射、低吸收高斯模式输出窗片的尺寸,获得窗片半径和厚度分别为46 mm和1.8 mm。通过理论分析各参数对高斯模式透射率的影响,并利用FEKO软件进行计算验证,获得高斯模式输出窗设计参数,从而为热核聚变用回旋振荡管的研究打下技术基础。     

固溶温度对电子束熔丝成形TC17合金组织与力学性能影响

研究了固溶温度对电子束熔丝成形TC17钛合金组织及力学性能的影响。结果表明：电子束熔丝成形TC17钛合金为柱状晶组织,柱状晶沿堆积高度方向生长,在柱状晶内部为细小的（α+β）板条构成的网篮状组织。随固溶温度升高,（α+β）→β转变更加充分,初生α相含量减少,初生α相含量和形态对材料的塑性有较大影响,因此塑性降低,强度上升。     

Fabricating Ni–Mn–Ga microtubes by diffusion of Mn and Ga into Ni tubes

Tubes of the ferromagnetic shape-memory alloy Ni–Mn–Ga of composition near the Ni₂MnGa Heusler phase can be used, alone or combined in structures, in magnetic actuators or magnetic refrigerators. However, fabrication of Ni–Mn–Ga tubes with sub-millimeter diameter by classical cold or hot drawing methods is hampered by the brittleness of the alloy. Here, we demonstrate a new process, where Ni–Mn–Ga tubes are fabricated by interdiffusion of Mn and Ga into drawn, ductile Ni tubes with 500 and 760 μm inner and outer diameters. After interdiffusion and homogenization of Mn and Ga at 1000 °C for 24–36 h, Ni–Mn–Ga tubes with ∼300 and ∼900 μm inner and outer diameters were obtained with homogeneous radial composition distribution, independently of the diffusion sequences (i.e., Mn and Ga diffused sequentially or simultaneously). Longitudinal composition was uniform over lengths of ∼1 mm, but variable over longer length due to incomplete process control. For two of the three diffusion sequences, a sizeable (20–80 μm) region exhibiting Kirkendall pores formed at the outer surface of the tubes. Magnetization values as high as ∼60 emu/g were measured, which is comparable to the magnetization of the Ni₂MnGa Heusler phase. X-ray diffraction on the tube with the highest magnetization confirmed the room-temperature structure as cubic austenite.     

添加剂对化学镀镍过程的影响

利用循环发技术及阴、阳极极化等方法研究了化学镀镍磷合金的沉积过程及加速剂的影响。结果表明,Ｎｉ＾２＋的还原反应与Ｈ２ＰＯ２＾－的氧化反应之间存在的着重要的相互作用即诱地共析作用;加速剂的加入,提高了Ｈ２ＰＯ２＾－的氧化能力,使反应激活能降低,因而加速了化学镀镍沉积反应。