低温超音速火焰喷涂特性研究

Characteristics of Low Temperature High Oxygen-Air Fuel Spray

由于冷喷涂技术的工作气压过高 ,限制了其应用。为此 ,应用多功能超音速火焰喷涂系统 (KY HVO/AF)焰流温度调节范围大的特点 ,设计了液料送粉系统和控制装置 ,扩大了喷涂低温工作范围 ,达到了低温喷涂工作温度和速度 ,实现了低温喷涂。采用压入式气液动力转换提供送粉动力 ,控制装置采用槽孔式计量方式 ,实现对流量的量化控制 ,整个数字化系统控制简单、可靠。以数值模拟的方式 ,分析了HVAF喷涂工作状态 ,液料流量、空气流量、煤油流量对焰流工作状态的影响 ,着重研究了不同液料流量时焰流状态的变化规律。结果表明 ,空气流量、煤油流量、液料流量是控制喷涂温度的三个重要因素 ,应用此技术成功地制备了纳米TiO2 涂层。

Multifunctional high velocity oxygen air spray (KY HVO/AF) has a wide temperature range, especially the low temperature range. A new low temperature thermal spraying technology based on KY HVO/AF was realized with a self made liquid feedstock control device. The liquid feedstock control device has the characteristics that the ratio of oxidizer and reducing agent is adjustable and the liquid feedstock flow rate is controllable. The flow capacities of air, kerosene and feedstock are the key factors for the thermal spraying process. Under the HVAF (high velocity air fuel spraying) state of KY HVO/AF, the thermal spraying parameters are tested and analyzed by adjusting the flow rates of oxygen, nitrogen, kerosene and feedstock. Based on the technique, the nanostructure TiO_2 coating is successfully obtained. The microstructures and phases of the powder and coating are investigated using XRD and SEM, respectively. The nanostructure coatings are formed without phase transformation and crystal growth during the spray process. The numerical results and experimental analysis prove that the low temperature range of high velocity air fuel spray is magnified, as well as the cold spraying.