Abstract We report measurements of the size, concentration, and hygroscopicity of ultrafine particles (UFPs) emitted during thermal spraying of ceramic coatings in an industrial setting. High concentrations (i.e., higher than 106 cm−3) of fractal-like UFPs were measured inside the spraying booths of the facility. The emitted UFPs were found to take up small amounts of water when exposed to elevated relative humidity (RH = 87%) within a Hygroscopic Tandem Differential Mobility Analyzer (HTDMA) system. The hygroscopicity of the sampled particles was distinguishably lower compared to those of the atmospheric background aerosol particles present in the breathing air. UFPs smaller than 90 nm that are produced by the thermal spraying process, exhibit hygroscopic factors less than unity in a systematic way. This behavior indicates that the particles were irregularly shaped at dry conditions, and that they underwent a shape change (i.e., restructuring) upon humidification inside the HTDMA. The fractal-like structure of process-emitted UFPs was further corroborated by Transmission Electron Microscopy (TEM) conducted on samples collected at dry conditions on site. Copyright © 2020 American Association for Aerosol Research

中文翻译：

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热喷涂过程中释放的超细颗粒的粒度分布和吸湿重组

摘要 我们报告了工业环境中陶瓷涂层热喷涂过程中排放的超细颗粒 (UFP) 的尺寸、浓度和吸湿性的测量结果。在该设施的喷房内测量了高浓度（即高于 106 cm-3）的分形 UFP。在吸湿串联微分迁移率分析仪 (HTDMA) 系统中，当暴露于升高的相对湿度 (RH = 87%) 时，发现排放的 UFP 会吸收少量水。与呼吸空气中存在的大气背景气溶胶颗粒相比，采样颗粒的吸湿性明显较低。由热喷涂工艺生产的小于 90 nm 的 UFP 以系统的方式表现出小于 1 的吸湿因素。这种行为表明颗粒在干燥条件下形状不规则，并且它们在 HTDMA 内加湿后经历了形状变化（即重组）。通过对在现场干燥条件下收集的样品进行的透射电子显微镜 (TEM) 进一步证实了过程发射的 UFP 的分形结构。版权所有 © 2020 美国气溶胶研究协会