Research On Key Technologies Of Particle Velocity Measurement

Based on the principle of aerodynamics, vacuum cold spray definition is that at room temperature and vacuum conditions, vacuum cold spray particle is accelerated by high pressure mixed gas to a certain speed, and the particle hit substrate to realize the coating preparation.The characteristics of the vacuum cold spray technology are high efficient deposition, low deposition temperature and compact coating structure. Ceramic particles are not easy to produce oxidation, phase change problem and organizational change, thus the vacuum cold spray study has been widely concerned. The speed of flight particle is one of the most important performance parameters in the vacuum cold spray technology, it influences the effect and quality of coating preparation directly, so it is important to study the particle velocity.Researchers in the vacuum cold spray laboratory of the domestic university are engaged in the research of vacuum cold spray particle velocity measurement, they collect particle flight voltage data by the particle data acquisition system platform which was developed by themselves, and use oscilloscope software to storage voltage data. Then the flying particle speed was measured by general analysis software. But the whole particle velocity detection method is low efficiency, and this method can not execute particle voltage data real-time collection, display and analysis at a time. Based on vacuum cold spray particle velocity measurement research, the vacuum cold spray particle velocity measurement software was developed and the software development technology and implementation plan is introduced. The software integrates particle parameters real-time acquisition, display and analysis function, and it can execute particle voltage data real-time collection, display and analysis at a time. The software improves the vacuum cold spray particle velocity detection experiment efficiency, and meets the further study requirements of vacuum cold spray technology.The main work of this paper can be summarized as follows:(1) Vacuum cold spray particle velocity detection software was developed, through memory-mapped files method in the software, the particle voltage signal can be real-timely saved in computer file, and the signal can be clearly displayed by TeeChart Control.(2) The particle signal was analyzed in time and frequency domain and the particle signal was processed by many neighbor average filtering method, fast fourier transform(referred to as FFT) bandpass and FFT low-pass filtering method, and compare performance parameters and characteristics of each particle signal processing results, the FFT[0-1.22MHz] low-pass filtering zero drift compensation combinated with 16 average neighboring filtering method was used to remove the signal noise.(3) The particle noise signal was processed through FFT[0-1.22MHz] low-pass filtering zero drift compensation combinated with 16 average neighboring filtering method, the effective particle pulse signal amplitude was determined according to the Gauss distribution characteristics of noise signal, and the effective particle pulse signal was obtained by using rectangle window function.(4) The effective particle pulse signal data was fitted through least square liner fitting method and the effective particle signals fitting equation coefficient was calculated,the latest particle rising edge and falling edge fitting data was got through signals fitting equation codfficient.(5) According to the latest fitting data,the velocity measurement algorithm was used to obtain the particle flight velocity value, take the average velocity as final experimental result, and the result was displayed in software.