MAGNETICALLY CONTROLLED DEPOSITION OF METALS USING GAS PLASMA

1 MAGNETICALLY CONTROLLED DEPOSITION OF METALS USING GAS PLASMA Quarterly Progress Report October-December 1996 DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recornmendation. or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Work Performed Under A U.S. Department of Energy Grant to the University of Idaho DE-FE07-93ID3220

Portions of this document may be illegible in electronic image products. huge are produced hm the best available original document.

MAGNETICALLY CONTROLLED DEPOSITION OF METALS USING GAS PLASMA Quarterly Progress Report October-December 1996 This document reports the status of grant DE-FEO7-93ID3220 for the October-December 1996 quarter. The objective of the grant is to develop a method of spraying materials on a substrate in a controlled manner to eliminate the waste inherent in present plating processes. The process under consideration is magnetically controlled plasma spraying. The project is no longer on schedule, Difficulties with modeling compressibie flow have caused a slip in the schedule. The milestone Code Development, dated January 1996 is now expected for completion in early 1997. Much of the work need to meet the iinal milestone to validate and verify the code has been completed, and a no cost extension of the project by approximately four to six months will result in successll completion of the project. The field equations have been developed and were reported in the April-June 1994 Progress Report. The equations for the external magnetic field were reported in the July-September 1994 progress report. The field equations have been cast in a format that allows solution using Finite Element (FE) techniques. The development of the computer code that will allow evaluation of the proposed technique and design of an experiment to prove the proposed process is underway. The basic numerical technique were reported in the October-December 1995 progress report, and code development and verification are underway (see Attachment 1). A parallel effort to evaluate a improved numerical techniques, the Integral Element Method (EMJ, is continuing The April-June 1995 report presents results of two of the standard problems I that are being used to validate and veri& the fluid portion of the code. The July-September 1995 status report presented the results of an ASME Benchmark problem that has been used to verity the addition of heat transfer, the energy equation, to the code. Compressibility has been added to the current code, and preliminary solution of a fluid jet problem was presented in the October-December 1995 report that is similar to the h a l configuration that must be analyzed. This case is being used to validate and veri@the code. Difficulties with the boundary conditions have been encountered and have been solved. Work in 2 I #12, October. 1996 I

the.july-september 1996 quarter was centered on performing validation and verification runs on the compressible fluid solution. Temperature induced buoyancy calculation are complete. Testing of the combined conservation of mass and momentum, conservation of energy, and the ideal gas law has been tested for the constant pressure, heat addition problem. The assumption of constant pressure, which could have greatly reduce the calculation difficulties encountered with compressible flow was evaluated, last quarter. This simplified formulation was found to be unacceptable for the final problem since a stagnation point exist on the substrate that causes a siizable increase in pressure at that point and invalidates the constant pressure assumption. This quarter attention was returned to the full formulation of the conservation equations, and results for a free jet and a stagnatingjet are presented. Seminars were given at Idaho State University and the Idaho Research Center at NZ in early December. Copies of the presentation are appended to.this report. These types of presentations are considered important to the validation effort, and give the researchers valuable feed back fiom knowledgeable Computational Fluid Dynamics (CFD) experts and Plasma Plating experts. Background Thin layers of secondary material are plated on substrates either by plating or spraying processes. Plating operations produce large amounts of hazardous liquid waste. Spraying, while one of the less waste intensive methods, produces "over spray" which is waste that is a result of uncontrolled nature of the spray stream. In many cases the over spray produces a hazardous waste. Spray coating is a mature process with many uses. Material can be deposited utilizing spraying technology in three basic ways: "Flame spraying", direct spraying of molten metals andor plasma spraying. This project is directed at controlling the plasma spraying process and thereby minimizing the waste generated in that process. The proposed process will utilize a standard plasma spray gun with the addition of magnetic fields to focus and control the plasma. In order to keep development cost at a minimum, the project was organized in phases. The fist and current phase involves developing an analytical model that will prove the concept and be used to design a prototype. Analyzing the process and using the analysis has the potential to generate significant hardware cost savings. Model Checkout Work on the finite element program with the full compliment of conservation equations was resumed this quarter. Alternate variable sets are also being considered that are more natural to the formulation. 3 812, October, 1996

Results fiom a fiee jet with the velocity, temperature and density set to unity (Figure 1) has been calculated to veri@the code calculation. This case will be compared to published solutions to fiee jet flow for code validation using a compressiblejet prior to adding the magnetic field equations. A case with ajet impinsing on a wall is also being considered, since this is the type of configuration that will be used to simulate the velocity, pressure, temperature and density fields for the plating process. Figure 2 shows the overall velocity field obtained with the jet impinging on a wall. Results appear reasonable, but as yet are inconclusive. Figures 3, and 4 are expanded plots of the velocity field at the jet entrance and the jet impingement point respectively. Again, results appear reasonable, but are not yet verified or validated. Attached to this report are copies of overheads that were used by two of the researchers in seminars at Idaho State University (ISU) and the Idaho National Engineering Laboratory(INEL). Both seminars were given on December 6, 1996. The Idaho State seminar was given to the facility and graduate students at the Pocatello Campus of ISU. This presentation was video conferenced to the Idaho Falls Center for higher learning. The INEL presentation was given at the Idaho Research Center in Idaho Falls. Presentations of this sort allow the researchers to present methods and results to others involved in simular research. The presentation are a form of peer review, and valuable comments and suggestions result. The work was well received by both groups which contained both ComputationalFluid Dynamic (CFD) experts and plasma plating experts. Status The milestone associated with completing the coding in January is not complete (Attachment 1). However, by combining the development work and the code verification work, the projected slip will be minimized. The final milestone scheduled for February will be completed in the April time fiame. Attached is a list of the milestones fiom the grant updated to be consistent with a FY 1994 projects start. The expected completion dates of the last two milestones is included on this attachment. Reference 1. Pai, Shih-I, Fluid Dynamics of Jets, D.Van Nostrand Company, New York. 1954 4 $12, October, 1996

Attachment 1 July - September 1996 Status Report Grant DE-FE07-93ID3220 Phase I: 1. Formulate Equations. a. Complete Literature Search. b. Evaluate coupled MHD-Fluid dynamic equations set. c. Perform scoping calculations. 2. Evaluate numerical techniques 3, Generate computer code and solve equations numerically. a. Code Development b. Code Verification April 1994 April 1995 April 1995 July 1995 Complete Complete Complete Complete January 1996 Expected 2/97 Feb. 1997 Expected 4/97

, Figure 1, Free Jet, velocity,temperature and density are all unity 6 #13. January 15,1997

PI01 9. hql Figure 2, Jet Impinging on Wall at 10cm. Entire Flow field, T=3OO0K,Vavg=.01 7 #13, January 15,1997

Figure 3, Jet Impinging on Wall - Jet entry point 8 813. Jmuvy 15.1997

Figure 4, Jet Impinging on wall, at the wall 9 #13, J m q IS, 1997

APPENDIX Overheads Used in December 6,1996 Presentations at Idaho State University and The Idaho National Engineering Laboratory Idaho Research Center 10 #13, Jyluyy 15,1997 - -

Magnetically Controlled Deposition of Metals Using Gas Plasma Robert R. Stiger And Satoru T. Yokuda December 6, 1996

This presentation will present a description of the project, and results to date w I I cl The progradproject The process being investigated Nurner ic a1 t e chi. que s being utilized Equation sets Result4

The Project Plan allows for 2 Phases Grant to U of1 is in place for Phase 1.Phase 1 Scoping calculations to assess viability Develop a computer model of the process * Assess Viability Calculate design parameter for a prototype H a a =Phase 2 b a.. *. I Laboratory test of the prototype

Schematic of a Plasma Spray Unit Target

E d) r K mu v d) m 0 n 0 & h 0 0 r 8 3 0-0

The Solution to the System Equations are 'I being Modeled Using 0 Two Different Numerical Techniques Finite Elements - Method of Weighted Residuals - Galerltin Technique Integral Element Method - Solves the integral equations - Uses elements and shape factors developed for finite element technique Both Methods Result in a System of non-linear simultaneous algebraic equations.

-- The Finite Element Method : Converts the integral equation to a differential equation (DE) by: Converting the surface integral to a volume integral using the divergence theorem (GausdGreen) b Collecting all the terms in one volume integral that is equated to zero b Recognizing that the kernel of the integral must be zero.

Finite Element Method (continued): An approximate solution is assumed dx Since the approximation is not exact a residual or error term results. Dp d 2h (x) + Q dx' = R(x) + 0

Finite Element Method (continued): Since the assumed solution does not satisfy the eauation. The weighted residual method requires r-/ I U I Y(x) R(x) dx = 0 0 In The Gelerlcin Method the weighing function and the approximate solution are the same fimction. The integral formulation is used to generate a system of algebraic equations. The method uses continuous piecewise smooth fbnctions for approximating the unknown(s)

The IEMSolves the Basic Integral Form of the Conservation Equations + ["Sources" dv V 4

,. Easily Understood Multi-node Elements are defined,the Fluxes and Volume Generation Terms are Evaluated Directly FVariabIes are Evaluated in the Elements using Shape Factors,Contribution Approach used to Generate a System of Algebraic Equations -~

7 I, 6 I 9 node quadrilateral 4 2 I 6 node trianale Area Associated with ~ ~ Each Node

The Calculation of Fluxes is carried out CCW & BCs are recognized: +- 4- -e +. -. I -w -- External Surface hternal Node The External Boundaries can be caleutated or input

9 U 4 : 0 CI \ + I? IS + L 3 0 U IS 1s Q -32 + u) D L 3 u) U

1 Q I i 0 * os.rl 7 w" nl + 1 e *D e I1 I1 I to x D 0 0 Q II 3 II

IEM Compressible Checkout Heat Flux BC - Energy Equation Check 3 2.8 2.2 I 0.02 0.04 X 0.06 0.08 0.1

EM Compressible Checkout Heat Generation - Energy Equation 4.5 i 2 I 1 I I 1 1-0 0.02 0.04 0.06 0.08 0.1

Incompressible Flow in a Square Cavity with Quadrilateral EIements (Re=lOOO)..

Incompressible Flow over a Backward-Facing Step with Quadrilateral Elements (Re=l000)

IncompressibIe Flow over a Backward-Facing Step with Heat Flux (Quadrilateral Elements) (R~533 and Pr-560) -J. O?i -!I. 305

Natural Convection Flow caused from Heated Walls

Compressible Flow caused from Heat Source

Jet fiom a Wall using Compressible Fluid 7 7 7 7 7 4

Jet fkom a Wall using Incompressible Fluid > =- W! =- F- 7 7 5 P 1 I

There is still much to be done: Finish check out of the compressible code Add the Magnetic Field Equations The external field equations have been solved Include the plating material