1、 INCH - POUNDMIL-STD 869D (USAF) 01 March 2007 SUPERSEDING MIL-STD-869C 20 October 1988 DEPARTMENT OF DEFENSE STANDARD PRACTICE FLAME SPRAYING This document is inactive for new design. AMSC: N/A AREA: MFP Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,
2、-,-MIL-STD-869D FOREWORD 1. This Military Standard is approved for use by 309MXSG/MXRL, Department of the Air Force, and is available for use by all departments and agencies of the Department of Defense. 2. This standard provides guidance on the process of flame spraying for the Air Force repair, ac
3、quisition, and manufacture of parts and/or spare parts on the landing gear of all military aircraft. 3. Beneficial comments, recommendations, additions, deletions, and any pertinent data, which may be of use in improving this document, should be addressed to 309MXSG/MXRL, Hill AFB, UT 84056-2609 or
4、309MXSG/MXRLhill.af.mil. Since contact information can change, you may want to verify the currency of this address information using the ASSIST Online database at http:/assist.daps.dla.mil. ii Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-8
5、69D CONTENTS PARAGRAPHS PAGEFOREWORD i1. SCOPE 11.1 Scope 1.2 Process 11.3 Classification 1.3.1 Types 12. APPLICABLE DOCUMENTS 1 2.1 General 12.2 Government Documents 1 2.2.1 Specification, standards, and handbooks 1 2.3 Order of Precedence 2 3. DEFINITIONS 2 4. GENERAL REQUIREMENTS 2 4.1 Materials
6、and Equipment 2 4.1.1 Wire/Flame Spray System 2 4.1.2 Thermo Spray System Powder 2 4.1.3 Plasma Spray System Powder 2 4.1.4 Wire/Arc Spray System 3 4.1.5 Abrasive Blasting Equipment 3 4.1.6 Flame Spray Wire 3 4.1.7 Flame Spray Powders 3 4.1.8 Gases 44.2 Bond Strength 4.3 Coating Material 4 4.4 Spray
7、ing Parameters 4 4.5 Cooling While Spraying 5 4.6 Selected Areas 5 4.7 Coating Thickness 5 5. DETAILED REQUIREMENTS 5 5.1 Procedure 55.1.1 Vapor Degreasing 5 iii Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-869D CONTENTS PARAGRAPHS PAGE5.1
8、.2 Masking 5 5.1.3 Abrasive Blast 5.1.4 Preheat 6 5.1.5 Spraying 5.1.6 Remove Masking 6 5.1.7 Sealing Sprayed Coating 5.1.8 Finish Machining and Grinding 6 5.2 Quality Control 6 5.2.1 Workmanship 5.2.2 Testing 6 5.2.2.1 Test for Bond Tensile Strength 7 5.2.2.2 Hardness Test 7 5.2.3 Certification of
9、Operators 8 5.2.4 Qualification of Operators 6. NOTES 8 6.1 Intended use 6.2 Subject term (key word) listing 8 6.3 Changes from previous issue 8 CONCLUDING MATERIALS 8 iv Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-869D 1. SCOPE 1.1 Scope
10、. This standard covers the materials, procedures, and equipment for flame spraying of parts. 1.2 Process. Flame spraying is defined as the process of melting materials in a heating zone and propelling them in the molten state onto a part to form a coating. This process can be applied to build up wor
11、n areas on parts, for abrasion resistance and/or corrosion protection. It is not intended to rebuild damage by nicks, gouges, etc; without building an entire area. 1.3 Classification. 1.3.1 Types. The four types of flame spraying covered in this standard are as follows: 1.3.1.1 Type I. Wire System:
12、Spraying materials in a wire form using oxygen-acetylene/hydrogen/propane, etc. 1.3.1.2 Type II. Powder: Thermo process, spraying materials in a powder Oxygen, acetylene or hydrogen. 1.3.1.3 Type III. Powder: Plasma process for spraying materials in a powder form utilizing a non-transferable electri
13、c arc with nitrogen. Argon and helium as a secondary gas with or without hydrogen. 1.3.1.4 Type IV. Wire Arc Spraying Process: Arc spraying system, simultaneously and continuously feeds two metalizing wires at a uniform rate of speed through electrically charged contact blocks. 2. APPLICABLE DOCUMEN
14、TS2.1 General. The documents listed in this section are referenced throughout this standard. While every effort has been made to ensure the completeness of this list, standard users are cautioned that they must meet all referenced requirements of the documents cited, whether or not they are listed i
15、n this section. 2.2 Government Documents. 2.2.1 Government specifications, standards, handbooks, and commercial item descriptions. The following specifications, standards, handbooks, and commercial item descriptions form a part of this document to the extent specified herein. Unless otherwise specif
16、ied the issues of these documents are those cited in the solicitation or contract. 1 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-869D DEPARTMENT OF DEFENSE FEDERAL SPECIFICATIONS BB-A-106 Acetylene, Technical, Dissolved BB-H-886 Hydrogen
17、BB-O-925 Oxygen, Technical, Gas and Liquid DEPARTMENT OF DEFENSE STANDARDS MIL-STD-866 Grinding of Chrome Plated Steel and Steel Parts (Inactive) Heat Treated to 180,000 PSI or over. (Copies of these documents are available from the Standardization Document Order Desk, 700 Robbins Avenue, Building 4
18、D, Philadelphia, PA 19111-5094 or http:/assist.daps.dla.mil.online/start/. 2.3 Order of Precedence. In event of a conflict between the text of this document and the references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes laws and regulations
19、 unless a specific exemption has been obtained. 3. DEFINITIONS: Not applicable. 4. GENERAL REQUIREMENTS 4.1 Materials and Equipment. 4.1.1 Wire/Flame Spray System. The wire system shall include either a compress air powder gun or an electronically controlled gun. Necessary air filtering shall be cap
20、able of delivering oil free and moisture free air. Gas and oxygen regulators shall be two stage regulators. Fuel gas flow meters and regulators must be equipped with flash back valves. Air pressure regulators shall be an OSHA approved type. Hoses, wire control and straightening units shall complete
21、the system. 4.1.2 Thermo Spray System Powder. The powder spray system shall include a spray gun that is capable of delivering flow rate. Regulators shall be of the two stage type. Fuel gas regulators and flow meters must be equipped with flash back valves. Air regulators shall be OSHA approved. Hose
22、s and optional equipment shall complete the system. 4.1.3 Plasma Spray System Powder. The plasma system shall include a plasma gun capable of operating on nitrogen. Argon or helium is primary gases with or without hydrogen as the secondary gas. The gun may be either a hand held or machine mounted ty
23、pe. a. The plasma gun shall be capable of spraying coatings of powdered materials that have been heated to a plastic or molten state by a highly ionized gas stream passing through a non-transferable electric arc capable of reaching temperatures of 30,000F or higher producing coatings with bond stren
24、gth of 4.000 to 12,000 psi or higher. 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-869D b. The power supply unit shall not be less than 40 (KW) capacities at 100% duty cycle. c. The power feeder unit shall be capable of supplying a meter
25、ed and constant flow of powdered material to the gun. d. Extension equipment capable of spraying at a 90 angle for holes may be incorporated as a component part. e. Control unit, heat exchanger, approved gauges, flow meters, hoses, power cables, and cooling devices shall complete the system. 4.1.4 W
26、ire/Arc Spray System. The arc spray system shall consist of a gun capable of simultaneously feeding two wires at a controlled rate of speed, and delivering a fine atomized spray on a prepared surface. The gun shall be capable of producing coatings with bond strength of not less than 4,000 psi. a. Th
27、e gun shall be hand held or machine mounted and be capable of controlling wire feed rate. The gun shall also be capable of operating solely on compressed air and/or electrical current. b. The power supply unit shall be capable of delivering amperage and voltage at 100% duty cycle. c. The control uni
28、t shall be compatible with automatic traverse equipment, and include air, amperage and voltage controls and monitors. d. Wire control units shall include wire straighteners. e. Hoses, lines and cables will comprise the balance of the system. 4.1.5 Abrasive Blasting Equipment. Abrasive blasting equip
29、ment is required to roughen areas to be flame sprayed. Parts should be previously cleaned. Particular care should be taken to keep abrasive grit from contaminating surrounding area. Blasting equipment should be used solely for preparing parts for flame spray. Manufacturers recommended procedures sho
30、uld be followed. 4.1.6 Flame Spray Wire. Only wires specifically manufactured for flame spray shall be used otherwise specified by the responsible engineering authority. The chemical composition of the material to be used shall be specified in the contract or purchase order for the materials. See ma
31、nufacturers handbook and current technical bulletins. 4.1.7 Flame Spray Powders. Powders used for flame spraying shall be designed specifically for flame spraying and the powder supplier shall so specify and certify that: a. The material has been inspected for size and that the size is in accordance
32、 with the size range spelled out in the purchase order. 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-869D b. All material meets the chemical composition requirements as specified in the purchase order. c. The material has been spray test
33、ed with oxygen-acetylene. Oxygen-acetylene combustion flame and plasma flame spray equipment, whichever is applicable. Insure that coatings can be produced that are smooth, uniform, and free from cracks and voids with required bond strength. d. Material meets requirements of engineering and industry
34、 standards. 4.1.8 Gases. The following gases shall be used flame spraying: GAS SPECIFICATION TYPE Oxygen BB-O-925 Commercial Acetylene BB-A-106 Commercial Propane Commercial Hydrogen BB-H-886 Commercial 4.1.8.1 Gases for plasma flame spraying. Gases for the plasma flame spraying process shall be as
35、follows: GAS SPECIFICATIONSHydrogen Pre-Purified 99.5% Max-Oxygen Content 0.05% Max-Dewpoint -76F (-60C) Nitrogen Pre-Purified Max-Oxygen Content 0.002% Max-Dewpoint -76F (-60C) Argon High Purity 4.2 Bond Strength. Flame sprayed coatings have bond strengths ranging from 3.000 to a maximum 12.000 psi
36、. Coatings should only be used where the bond strength of the coating is approved for a specific application by engineering authority. 4.3 Coating Material. The coating material must be specified by the responsible authority. Metallurgical laboratory testing may be required where deemed necessary. 4
37、.4 Spraying Parameters. Air, fuel gas, primary and secondary pressures and flow settings for the spraying of each material shall be in accordance with those recommended by the equipment manufacturers instructions manuals for each process. 4 Provided by IHSNot for ResaleNo reproduction or networking
38、permitted without license from IHS-,-,-MIL-STD-869D Gun to work distance shall be established from the instruction manuals or bulletins, or by testing and analysis. 4.5 Cooling While Spraying. Part and coating temperatures must be controlled to prevent warpage of the substrate and failure of the coa
39、ting. The maximum substrate temperature is: 350F (176.6C) for Steel 225F (107.2C) for Aluminum The time at this temperature is not to exceed one (1) hour. 4.6 Selected Areas. If selected areas are to be flame sprayed, the surrounding areas must be masked with available tapes or masking compounds. Ke
40、yways and oil holes may be masked with carbon plugs or polished metal inserts or silicone rubber. 4.7 Coating Thickness. Some coatings have thickness limitations. Coating thicknesses shall be specified by applicable documents, if thickness is not specified then the finish machine coating shall not e
41、xceed 0.030 inch. a. A minimum of 0.010 inch over final dimension shall be allowed for grinding. Follow manufacturers recommendations. b. For corrosion protection, a minimum coating thickness of 0.003 to 0.005 inch is required. 5. DETAILED REQUIREMENTS 5.1 Procedure.a. All parts must be machined and
42、 cleaned if required prior to flame spray. b. High tensile steel and high strength aluminum part, which have been pre-machined must be stress relieved by shot peening areas to be flame sprayed. c. Areas to be flame sprayed, which have been plated shall have these finishes removed from area to be spr
43、ayed by either chemical or mechanical means. Blasting is not acceptable method of removal. 5.1.1 Vapor Degreasing. All parts shall be vapor degreased prior to surface preparation unless otherwise specified by engineering. 5.1.2 Masking. Mask all areas not to be abrasive blasted or coated. 5.1.3 Abra
44、sive Blast. Abrasive blast areas, to be coated for the removal of oxidation, follow the manufacturers recommended procedure and bulletins unless otherwise specified by engineering. 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-STD-869D 5.1.4
45、Preheat. Preheat before spraying to remove all moisture and provide expansion. Manufacturers bulletin should be followed regarding substances and material to be sprayed. Temperature control may be accomplished using temp stick or pyrometers. 5.1.5 Spraying. Spray the area to be coated using the gun
46、to work distance recommended by the equipment manufacturers for the material being sprayed. The direction of the metal spray should be as close to 90F as possible with the surface being coated and never less than 45F. The coating shall be allied in multiple passes. Complete area coverage must be mad
47、e with each pass before the next pass is started. Spraying will continue until the coating thickness plus finishing allowance has been completed. 5.1.6 Remove Masking. Remove masking material. 5.1.7 Sealing Sprayed Coatings. All flame sprayed parts should be sealed unless intended as a bearing surface or as otherwise specified by engineering. Only, quality commercial sealers shall be used. Type of sealer used depends on the type of environment parts will be subjected to. 5.1.8 Finish Machining and
