The critical velocity is an important parameter in cold spraying, which determines the deposition efficiency under a given spray condition. The critical velocity depends not only on materials types, but also on particle temperature and oxidation conditions. In the present paper, three types of materials including copper, 316L stainless steel, Monel alloy were used to deposit coatings by cold spraying. The critical velocities of spray materials were determined using a novel measurement method. The oxygen content in the three powders was changed by isothermal oxidation at ambient atmosphere. The effect of oxygen content on the critical velocity was examined. It was found that the critical velocity in cold spray was significantly influenced by particle oxidation condition besides materials properties. The critical velocity of Cu particles changed from about 300 m/s to over 610 m/s with the change of oxygen content in powder. It is evident that the materials properties influence the critical velocity more remarkable at low oxygen content than at high oxygen content. The results suggest that with a severely oxidized powder the critical velocity tends to be dominated by oxide on the powder surface rather than materials properties.

No abstract

This version is available at https://strathprints.strath.ac.uk/60792/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the The experimental study of a pseudospark discharge sourced electron beam with post acceleration (PA) is presented. The PA circuit was used to drive a W-band extended interaction oscillator. The experiments showed a significant increase in the output power, with 200 W at 94 GHz measuring corresponding to a 5 times increase in the output power as compared to when post acceleration is not used. The microwave device developed has the advantage of not requiring an external magnetic field making it a low cost, compact, and portable sub-terahertz radiation source. Published by AIP Publishing.[http://dx

This version is available at https://strathprints.strath.ac.uk/59731/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the During its conductive phase, a pseudospark discharge is able to generate a low energy electron beam with a higher combined current density and brightness compared with electron beams formed from any other known type of electron source. In this paper, a configuration is proposed to post-accelerate an electron beam extracted from a single-gap pseudospark discharge cavity in order to achieve high quality high energy intense electron beams. The major advancement is that the triggering of the pseudospark discharge, the pseudospark discharge itself and the post-accelerating of the electron beam are all driven by a single high voltage pulse. An electron beam with beam current of ~20 A, beam voltage of 40 kV and duration of ~180 ns has been generated using this structure. The beam energy can be adjusted through adjusting the amplitude of the voltage pulse and the operating voltage of the whole structure which can be varied from 24 to 50 kV with an efficient triggering method under fixed gas pressure below ~10 Pa.