热喷涂用送粉器国内外现状及发展

本文归纳介绍了几种常用热喷涂送粉器的结构原理,分析比较了不同类型送粉器间的差异和适用范围,收集了近年来国内外商品化设备的信息,提出了国内热喷涂送粉器的发展趋势。     

热障涂层无损检测技术研究进展

为提高发动机的涡轮前温度和热端部件服役寿命,热障涂层（TBCs）被广泛应用于燃气涡轮发动机。热障涂层具有多相、多界面和非均质特性,且其服役工况恶劣复杂。寻找一种可以表征涂层显微组织、缺陷、热物性、应力等反映涂层质量和剩余寿命的无损检测方法,对发动机的热端部件安全性和可靠性至关重要。文中综述了超声检测技术（UT）、声发射技术（AE）、红外热成像技术（IRT）、阻抗谱技术（IS）和光激发荧光压电光谱技术（PLPS）的原理以及其在热障涂层无损检测中的研究应用,并详细介绍了太赫兹时域光谱（THz-TDS）技术及其在热障涂层中的应用。最后总结了上述无损检测方法的检测能力,并对热障涂层无损检测方法进行展望。     

高、低喷涂功率下内送粉等离子喷涂YSZ粒子熔化状态研究

等离子喷枪采用内送粉方式后,喷涂功率对YSZ热障涂层微观结构和性能有着独特的作用,高功率下制备的涂层结合强度反而较低。本文研究了内送粉等离子喷枪在高功率(42.5 kW)和低功率(33.6 kW)时距喷嘴出口90 mm处的粒子熔化状态(粒子温度、粒子飞行速度、粒度分布及扁平粒子形貌)。研究结果表明,采用高喷涂功率时,由于等离子射流较高的热焓值使粒子迅速熔化并细化成粒径较小的熔滴,熔滴在撞击基体前发生再凝固降低了扁平粒子间的粘结。涂层出现横向裂纹,结合强度平均值仅为22.58 MPa。采用小喷涂功率时,既能保证粒子熔化良好又不会导致粒子发生明显细化。涂层结合强度平均值为37.25 MPa,随试片弯曲180(°)后仅出现一处剥落,1100℃炉中保温10 min取出后迅速置于水中淬冷130次后,试片中部涂层完好,显示出良好的抗热震性能。     

Prediction of the Nutrient Content in Dairy Manure Using Artificial Neural Network Modeling

Nutrients in animal manure are valuable inputs in agronomic crop production. Timely and reliable information on animal manure nutrient content will facilitate the utilization of manure as organic fertilizer and reduce any associated potential environmental problems. The objective of this study was to investigate the feasibility of using multiple linear regression (MLR), polynomial regression, and artificial neural network (ANN) models to determine nutrient content in dairy manure. Fresh manure samples (n = 86) from Holstein dairy cattle were collected from 34 dairy farms located in Beijing city, China. All samples were analyzed for nutrient content (ammonium nitrogen, total potassium, total nitrogen, and total phosphorus) by standard laboratory methods. The physicochemical properties (specific gravity, electrical conductivity, and pH) of dairy manure samples were measured. Relationships between nutrient content and physicochemical properties were explored by MLR, polynomial regression, and ANN models. Several parameters (R², modeling efficiency statistic, mean squared error of prediction, mean bias, linear bias, and maximum bias) were calculated to evaluate model performance. The residual analysis results indicated that all MLR models for the testing data set had significant mean and linear bias. When compared with MLR and polynomial regression models, the ANN model for all nutrient contents had better performance with higher R² and modeling efficiency statistics and lower mean squared error of prediction, mean bias, linear bias, and maximum bias. These findings demonstrated that the ANN model may be an appropriate tool to predict dairy manure nutrient content.     

Vacancy-ordered yttria stabilized zirconia as a low-temperature electronic conductor achieved by laser melting

Laser melting is known to be capable in initiating thorough evolution in microstructure and bringing novel functional performance in metals. But realization of this potential in ceramics only reaches a preliminary stage that needs further investigation. Here we demonstrate zirconia, traditionally an insulative ceramic at low temperature, could be transformed into an electronic conductor with the conductivity on order of 10⁻³ S⋅cm^-1 at room temperature by a simple laser melting process without inducing metallic phases. Transmission electron microscopy and ab-initio simulation show that oversaturated oxygen vacancies, together with their ordered metastable distribution along <001 > , are introduced during this non-equilibrium process, and result in a clear defect level significantly narrowing bandgap to less than 1 eV, leading to the considerable electronic conductivity. These results identify a strategy of utilizing this non-equilibrium method in oxide ceramics to realize some unconventional performances determined by metastable structure thoroughly altered down to atomic level.     

从米糠中提取植酸钙的工艺研究

对米糠中提取植酸钙的工艺进行了研究.以酸浸pH值、浸泡时间、液料比为影响因素,进行了3因素3水平正交试验.经多次重复试验,结果表明最佳工艺为:酸浸pH值2.0,浸泡时间5h,液料比8∶1;在最佳条件下,植酸钙的提取率为9.06％.通过对植酸钙标准品和所提取物质的红外谱图的比较,证实所提取物质为植酸钙粗品.     

HPLC法测定饮料中日落黄含量的不确定度评定

对HPLC测定饮料中的日落黄含量测定结果进行不确定度分析,通过对各影响因素的不确定度评定,标准曲线拟合对饮料中合成着色剂的测量结果不确定度的影响最大,其次是样品处理回收率和实验重复性引入的不确定度对实验结果也有较大的影响。结果表明,饮料中日落黄的含量为(81.61±2.80)mg/kg,k=2。     

三手指拉拔式红花采摘末端执行器的设计

通过分析人手工采摘红花时人手指所处的形态,提出了三手指拉拔式红花采摘末端执行器的设计方案.通过采收期红花物料拉拔特性的测量与统计分析,确定机械采摘红花所需最大拉拔力,并通过红花植株生物特性分析,设计计算末端执行器采摘手指及其它关键部件.利用运动学仿真分析三手指拉拔式末端执行器在工作过程中夹持力、运动位移和时间的关系,最...     

肉鸭掏膛机改进设计与仿真分析及试验

针对中国肉鸭屠宰过程中,机械自动化程度低、生产效率低、设备依赖进口等问题,设计一种自动掏膛机。阐述掏膛机整机结构与工作原理,对其关键部件掏膛机械手单元进行分析,并结合凸轮曲线相关理论进行协调性设计和曲线修正与优化,利用creo3.0建立多轨迹空间圆柱凸轮的三维模型,并进行运动学仿真,对主轴进行了扭转刚度校核。验证试验结果表明:该型掏膛机在不同产量下,平均内脏器官数量完整度为94.5%,平均内脏器官形态完整度为91.06%。     

喷涂参数对内送粉等离子喷枪制备YSZ涂层微观结构和性能的影响

为了进一步提高大气等离子喷涂YSZ热障涂层性能并降低其成产成本,开发了内送粉等离子喷枪.本文采用Spray Watch 2i在线监测系统测量了YSZ粉末粒子温度和飞行速度,采用实验室手段表征了涂层的微观结构、结合强度、弯曲性能和抗热震性能.研究结果表明,内送粉方式下喷涂距离对涂层微观结构和性能的影响规律与外送粉相似,而电流和主气流量表现出了独特的作用效果：随电流的增大,涂层综合性能先增加后降低,高电流下制备的涂层结合强度较低;在30～50 L/min范围内,增大主气流量可显著提高涂层结合强度.与外送粉最优参数制备YSZ涂层相比,内送粉时的功率消耗大幅降低,但粒子熔化效果明显增强,相同送粉速率下粉末沉积效率略有增加,涂层热循环寿命有所提高.