Multilayer films by spraying on spinning surface — Best of both worlds

The layer-by-layer buildup of poly(styrene sulfonate), poly(diallyldimethyl ammonium) and/or TiO₂-nanoparticles was carried out using an automated system which allowed spraying the polyion solutions on a spinning substrate. The different spraying and spinning arrangements were studied. The films were prepared by varying ionic strength, electrolyte species (NaBr and NaF) and spraying time. The results were compared to the films prepared by using the traditional dipping method. Depending on the electrolyte and the ionic strength the thickness of the films prepared with spraying on spinning substrate was thinner than or equal to the dipped films. It was found that addition of salt on spraying solutions is necessary in order to prepare thin films with a good quality. Spraying on spinning substrate generated evenly occupied smooth surfaces. The benefits of the automated method are attributed to the noticeably lower solution consumption and to the fact that the film deposition process could be accelerated by a factor of 100 comparing to the traditional dipping method.     

An investigation of the nozzle’s atomization dust suppression rules in a fully-mechanized excavation face based on the airflow-droplet-dust three-phase coupling model

In order to suppress the diffusion of high concentrations of dust towards the operating area in a fully-mechanized excavation face effectively, this study constructed a mathematical model that describes the interactions among droplets, dust and airflows, and then validated the accuracy of the established model. Finally, under single-forced ventilation conditions, the dust suppression rules when different nozzles were used at different spraying pressures were investigated in detail. The results reveal that when different spraying schemes were used, the dust mass distributions in different regions along the tunnel were basically the same; they all first decreased, then increased and finally decreased. At a spraying pressure of 2–8?MPa, the spraying pressure and dust suppression efficiency followed a logarithmic function; however, with an increase in the spraying pressure, the dust suppression efficiency increased gradually at a declining rate. Under a spraying pressure of 8?MPa, the dust clusters in which the dust concentration exceeded 110?mg/m³ in the fully-mechanized excavation face were reduced significantly. Out of all the spraying schemes, the one using K2.0 nozzles at a spraying pressure of 8?MPa achieved the most favorable dust suppression performance, and the dust suppression efficiency in a fully-mechanized excavation face was as high as 86.1%; meanwhile, the proportion of respirable dust with a diameter smaller than 7?μm increased gradually from 16% to 27%.     

Liquid absorption capacity of carriers in the food technology

If a liquid should be sprayed on a powder that acts as a carrier, the Concentrated Powder Form (CPF) technology can be used. In the food industry, there is a large number of products available in powder form, which can be used as carriers for liquid components. But there is a big difference between them in view of the maximum liquid absorption capacity. To find out which attributes affect the liquid absorption capacity of these carriers, several natural substances and model particles with defined uniform diameter and spherical shape were loaded with increasing amounts of different liquids. The aim of this study is to find out more about the casual relationship between the characteristics of powders and liquids, as well as the loading capacity. Therefore, a correlation between the tapped density and the maximum loading capacity is discussed. To determine the maximum loading capacity, a simple method using a filter was developed.     

高性能单向导湿织物的制备研究

单向导湿织物因在提高织物热湿舒适性方面具有潜在的应用前景而受到人们的关注.文中分别利用印花法和喷淋法在棉织物单侧进行不连续的疏水整理制备了单向导湿织物,探讨了印花法的不同整理面积、不同整理图案对单向导湿性能的影响,并将印花法和喷淋法得到的织物进行对比,使用液态水分管理测试仪(MMT)对其单向导湿性能进行测试.结果 表明...     

用于喷涂设备的直流静电高压发生器的设计

通过对空气静电旋杯喷涂的分析研究,在已经市场化的设备基础上,设计了一种用于喷涂设备的直流静电高压发生器。设计表明进一步完善了设计要求。通过试验证明提高了EMI能力和减少了功耗,具有较好的保护性能。通过实际应用证明该发生器提高了设备的上漆率达85%以上,涂复率达90%以上,喷涂质量有所提高。还需进一步研究设计以便继续提高。     

氟碳清漆超临界CO2喷涂工艺的研究

本文测定了超临界CO2（SC-CO2）-氟碳清漆-稀释剂拟三元体系相图，用L9（34）正交表考察了温度、压力、CO2含量对含有超临界CO2涂料液雾化效果和喷雾锥角的影响．结果表明，当温度低于70℃、压力大于10MPa、CO2含量小于32％时均能使喷涂液处在稳定单相区，随着温度、压力和CO2含量的增大，雾化粒子变细，喷雾锥角变大．在14MPa、CO2含量32％（wt）和60℃下喷涂，其涂膜主要性能均达到了国家标准，喷涂过程VOC值降低了43．5％。     

曲面边缘均匀喷涂的路径分片规划方法

针对现有的切片法生成的喷涂路径在曲面边缘处喷涂不均匀的问题,提出一种基于点云模型的曲面边缘均匀喷涂的路径分片规划方法。该方法基于曲面点云模型,首先利用主成分分析法构建曲面外扩包围盒,基于外扩包围盒生成的主切片将曲面分片为一系列单条曲面,使得每一个单条曲面都对应于一条喷涂路径,再利用副切片将单条曲面分片为一系列单片曲面,使得每一个单片曲面都对应于一个喷涂路径点,以此生成喷涂路径。仿真结果表明：在期望涂层厚度为25μm时,对于规则边缘曲面,分片法获得的涂层厚度误差为4.33μm,比切片法减小了77.09%,涂层厚度标准差为0.81,比切片法减小了74.37%;对于不规则边缘曲面,分片法获得的涂层厚度误差为4.03μm,比切片法减小了77.42%,涂层厚度标准差为0.76,比切片法减小了73.15%。分片规划方法适应于规则和不规则边缘曲面喷涂路径规划,其在边缘处涂层均匀性优于切片法,实现了曲面边缘均匀喷涂。     

等离子喷涂技术研究与发展现状

本文从等离子喷涂设备、新型功能涂层、与等离子喷涂相关的测量技术等几个方面,综述了等离子喷涂技术的研究与发展现状。     

用热喷涂技术提高重载汽车同步齿环稳定性和寿命

本文研究了热喷涂工艺参数对钼合金性能的影响,选择了最佳参数进行喷涂,并将涂层应用到重载汽车同步齿环上,其性能指标和实车考验均达到德国大众公司标准。     

车载纳米TiO2装备喷洒均匀度计算模拟

根据纳米TiO2的特性,在全路况车上设计装备纳米TiO2喷洒装备,并在4种车速下对平面喷洒量进行数值计算模拟,利用Delaunay三角剖分法和MATLAB科学计算软件,对平面上纳米TiO2喷洒点的分布均匀度,通过三次样条多次插值计算,将喷头的喷洒点分布数据转换为网格型。对喷头的方形组合喷洒特性情况进行理论分析,结果表明在喷洒面积相同情况下,全路况车速为2.0m/s(7.2km/h)时,正方形组合布置喷洒点的数据分布较为均匀。