Praxair and TAFA Arc Spray Cobalt Alloy MXC

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1 Material Review: File: MXC Issue: Supercedes: Praxair and TAFA Arc Spray Cobalt Alloy MXC This material produces coatings which resist wear from abrasive particles, hard surfaces and fretting in high temperature environments. A coating of 106MXC material can also be used to resist heat and restore parts made of cobalt or cobalt alloys. The coating is machinable, and significantly harder than Praxair and TAFA's 76MXC. This material can be sprayed with any Praxair and TAFA Arc Spray gun. Praxair and TAFA 106MXC is being evaluated at several major manufacturers of aircraft engines as a cost-effective alternative to plasma sprayed materials that conform to PWA 1316 and PWA CAUTION: All Praxair and TAFA wires have been optimized for arc spraying. Use of alternate wires may cause problems such as excessive tip wear, spitting and feeding problems. Please use only Praxair and TAFA certified wires. Application Review: Praxair and TAFA 106MXC is used to produce wear resistant coatings, resist particle erosion at temperatures from F [ C], and is suitable for exhaust valves and seats. Forging tools and hot crushing rolls are also protected with 106MXC since it is very resistant to indentation from hard surfaces. Mismachined or worn parts may be rebuilt with 106MXC and remachined. Turbine air seals and turbine vanes coated with 106MXC withstand fretting in high temperature environments. Other applications include heat treating fixtures, and any manufacturing equipment that has temperature and erosion environments. MXC is a registered trademark of TAFA Incorporated, Concord, NH

2 Typical Composition: Nickel Chromium Tungsten Carbon Cobalt 10 percent 25 percent 8 percent 1 percent 56 percent Coating Physical Properties: Wire Size 1/16" (1.6 mm) Deposit Efficiency 64 Percent 1 Melting Point Bond Strength Coating Texture 2300 F (12 C) (approx.) 6700 psi (46 MPa) Variable 2 (see next page) Macrohardness Ra 1 Coating Density 7.4 g/cc 3 Finish Machined: Ground: Spraying: Spray Rate Coverage (wire consumption) 40- (microinches) Ra (microinches) Ra 6.7 lbs/hr/100 amps (3.0 kg/hr/100 amps) 0.9 oz/ft 2 /0.001" (1.1 kg/m 2 /100 microns) Spray Pattern parameters with primary air at psi (413 kpa) and secondary air pressure at 50 psi (345 kpa) and a 3" (7.6 cm) standoff produce the smallest spray pattern. Length of wire per lb 116 ft. (35.4 m) Depends on air pressure, standoff, nozzle cap and target size. Depends on air pressure - fine with high psi, average with medium psi, and rough with low psi Depends on atomizing air pressure and the use of. Page 2

3 Spraying Procedure: Coating Type 8830/ / Atomizing Air Pressure:Primary Secondary Nozzle Cap Blue ** Green Green Green Green Nozzle/Positioner Short ** Arc Load Volts a Amps b Standoff Inches Coating Thickness/Pass-mils Coating Texture-microinches aa Using excessive voltage reduces quality of coating. Voltage should be adjusted to give minimum noise and smooth arc operation. Excessive voltage causes larger particles and poor spray pattern. Too low a voltage will cause popping. Be sure not to overheat substrate even if this means stopping to allow cooling, use air jet cooling if greater speed is required. NOTE: air caps and positioners can be used in 8830 or 9000 systems. * P/N Arc Jet Air Cap ** P/N Arc Jet Modified Short (8830 & 9000) -- 4 For finer finish, raise air pressure at point of finish. 5 When using power lead extensions other than the normal 12 foot furnished, the voltage must be increased by approximately 3.4 volts per 50 foot extension; i.e. add 3.4 volts to the recommended voltage setting for a given wire if the extension is increased to a 50 foot length. 6 Can vary between depending on size of the part and traverse speed. Page 3

4 Finishing: An exceptionally good finish can be achieved by turning: Surface Speed Traverse Speed Depth of Cut 110 fpm (0.08 m/s) " ( mm) per rev " (.4-.6 mm) for first few cuts then " ( mm) to finish Coated tungsten carbide and ceramic tools can be used to obtain a finish of 32 microinches Ra. Grinding can also be used to obtain a good smooth finish. Dress frequently and do not permit coating to overheat. Cutting oil is not required. On the hardest coatings, pull out may be a problem if a cutting tool is used, but it is easier to produce a 20 microinch Ra finish using the correct grinding wheel and grinding technique. A 15 microinch finish can be obtained with care. Secondary finishing is required below 10 microinches. Use grinding wheels that meet the following specifications: Silicon carbide 37 C I hardness 8 porosity Vitrified open wheel Typical Grinding Setup: Wheel rpm: Med/High Shaft rpm: Low SFPM: High with the work running opposite the wheel Amount removed per pass (.013 mm) Use very light pressure and clean wheel. Super finishing with either silicon carbide or diamond cloth using a mineral base (non-sulfur) 5 to 10 weight hydraulic oil or kerosene can produce finishes below 10 microinches Ra by starting with 240 grit paper and progressing to 320, 400 0, 1200, and even If diamond cloth is selected, use a 9 to 15 micron particle size. The objective is to use the 240 cloth to completely remove the grinding marks from the 37 C wheel. Then, use the 320 cloth to remove the marks from the 240 cloth. Each successive cloth is used to remove the marks from the previous one. If one switches to the finer cloths too soon, a high polish will result on the "high spots", but many of the original deep grinding marks will remain. Speeds & Feeds Dry Grinding Wet Grinding Wheel Speed SFPM 00 (30 m/s) 00 (30 m/s) Work Speed SFPM (.3 m/s) 70 (.36 m/s), rough Wheel Traverse IPM 7 (3 mm/s) rough 12 (5 mm/s) 2.5 finish (1 mm/s) In Feed (inches) (.025 mm), rough (.013 mm) finish (.025 mm) (.013 mm) Coolant -- Water Soluble, 1 part coolant to 50 parts water Hazards: Observe normal spraying practices, respiratory protection and proper air flow pattern advised. For general spray practices, see AWS Publications AWS C2.1-73, chapter 11, "Recommended Safe Practices For Thermal Spraying" and AWS TSS-85, "Thermal Spraying, Practice, Theory and Application." Thermal spraying is a completely safe process when performed in accordance with proper safety measures. Become familiar with local safety regulations before starting spray operations. DO NOT operate your spraying equipment or use the spray material supplied before you have thoroughly read the Praxair and TAFA Instruction Manual. DISREGARDING THESE INSTRUCTIONS IS DANGEROUS TO YOUR HEALTH. Page 4

5 A Material Safety Data Sheet will be sent with each initial purchase and updated as required. The Information provided herein is believed to be accurate and reliable; however, results may vary with workpiece preparation and operator technique. Praxair and TAFA warrants only that the wires are free of defects in material and workmanship. No other warranty is expressed or implied. Copyright 2000 Praxair Technology, Inc. All rights reserved Telephone: Fax: Praxair, the Flowing Airstream design and Making our planet more productive are trademarks or registered trademarks of Praxair Technology, Inc. in the United States and/or other countries. Other trademarks used herein are trademarks or registered trademarks of their respective owners. Printed in the United States of America Telephone: Fax: TAFA is constantly improving its products, therefore specifications are subject to change without notice TAFA Incorporated is a Praxair Surface Technologies company. Page 5