Processes and apparatus for surface modification

摘要

An ultrasonic peening apparatus comprises an enclosure 102 for receiving at least part of a workpiece 103 and a component such as a sonotrode 101 vibrating at an ultrasonic frequency to impart energy to bombarding particles 104, surface augmentation material 107 being provided within the enclosure 102. An inlet such as a nozzle 106 may be provided for the surface augmentation material 107 and the inlet may be provided in a surface of the vibrating component 101. The surface augmentation material may be fluidized in a gas stream, provided in an aerosol 107 or as a component of the particles 104. The ultrasonic frequency may be between 15 and 100 kHz, the vibration amplitude may be between 0 and 300μm peak to valley and the workpiece may be between 1 and 300mm from the sonotrode 101. The particles 104 may be grit or shot, 0.1 to 10mm in diameter, between a density of 0.1 and 25 g/cm2 and the volume ratio between the articles 104 and the enclosure 102may be less than 50%. The enclosure 102 may be maintained below 150°C. The apparatus may be used to provide biocidal coatings or active coatings for medical devices such as implants.