DC arc plasma jet diamond film of residual stress and crack damage

Title: DC arc plasma jet diamond film of residual stress and crack damageAuthor: Tang DapeiDegree granted by: Southwest Jiaotong UniversityKeywords: DC arc plasma jet;; diamond film;; residual stress;; cracking damageSummary:Diamond film is a multi-functional performance of extraordinary materials, machining, aerospace, microelectronics manufacturing and many other fields with a wide range of applications. However, diamond films in the preparation process, the high residual stress cracking prone to membrane damage this issue has not yet been satisfactorily resolved. In this paper, prepared by DC arc plasma jet-standing diamond films were studied to plasma torch inside and outside the complex electrical, magnetic, thermal, variable and multi-field coupling strength of diamond films heat - stress coupling conditions for the study of target , the plasma flow and heat transfer as well as Magnetic lifter self-supporting diamond films in various stages of preparation for numerical simulation of stress, and reveal the large-size diamond films causes cracking damage and influencing factors.The main research work are as follows:1 by DC magnetron deposition of diamond films for the study plasma torch, in the classic Navier - Stokes (Navier-Stokes) flow and energy equations in the introduction of a number of source terms, including any external magnetic field and internal self-induced magnetic field caused by the Lorentz force, radiation cooling, Joule heating and Ar-H_2 mixed plasma due to temperature, pressure, electric field and concentration gradients caused by convection-diffusion, etc., and combined component mass conservation, the generalized Ohm's law and Maxwell's equations, the establishment of a plasma torch inside the magnetic fluid dynamics (MHD) model of multi-field coupling. http://www.999magnet.com/products/131-magnetic-lifter FLUENT software successfully on a secondary development, effectively coupling model for the construction involved in the MHD flow field, temperature field and electromagnetic field simulation. Obtained in a case with no external magnetic field, velocity field inside the plasma torch, the temperature field and current density field, as well as torch exit velocity and temperature distribution along the radial direction.(2) within the plasma torch above the MHD simulation results of multi-field coupling, the torch exit velocity, temperature and other parameters of the export conditions outside the deposition chamber as the torch plasma jet inlet conditions, the calculation of the establishment of a plasma jet fluid dynamics model. After using the FLUENT software secondary development of diamond film deposition chamber above the plasma jet flow and heat transfer simulation. Received plasma jet velocity and temperature fields, and also get the diamond film surface temperature distribution along the radial direction, as this paper later on the diamond film heat - coupled analysis of the foundation.3 the use of film / substrate system in the cooling process of the transient heat - coupled model, taking into account the coupling between temperature and strain effects on the film / substrate system in the cooling process of the temperature field and thermal stress field, and cooling to room temperature, the thermal residual stress field in a finite element numerical simulation. In the simulation, the film / substrate system is non-uniform cooling temperature field from initial conditions in the actual preparation of this paper under the conditions of multi-field coupling calculations, which makes the thermal stress and thermal residual stress field simulation results, not only the film / substrate thermal expansion coefficient differences in the impact, but also reflects the film / substrate system, the temperature non-uniformity of the point of impact, so the stress of the simulation results more realistic and accurate. Diamond films based on thermal stress and thermal residual stress field simulation, analysis of the diamond film off or cracking damage causes actual damage to the phenomenon of a more reasonable explanation.4 a unit, "death" technology, from the matrix of a self-supporting diamond films when heat redistribution of residual stress have been studied quantitatively diamond films has been the release of thermal residual stress, intrinsic stress of Calculating the proposed helpful comments.5 of the diamond film thermal residual stress and cracking damage to some of the factors affecting the results of their research for the residual stress of diamond films reasonable control, manufacturing process improvements and yield improvement, etc., have great reference value.Degree Year: 2009