ARMY TM 5-6115-612-34 NAVY AG-320B0-MME-000 e Quality The sprayed coating shall be adherent to the base material and shall have a uniform surface free from blisters, chips, or other objectionable imperfections not readily removable by finishing operations (1) Coatings shall be tree from cracks, excessive and massive oxides, and excessive porosity (2) Coatings  shall  be  essentially  tree  from  grit particles and contamination at the Interface between the coating and substrate f Rejections  Parts  on  which  the  sprayed  coating does not conform to the requirements of this specification,   or   to   authorized   modifications,   shall   be subject to rejection. g Approval Sources Metco type D-5 Plasma Spray Coating - Molybdenum. a Scope (1) Type This specification covers the procedure for plasma spray deposition of a molybdenum coating (2) Application. Primarily to provide a molybdenum coating for dampening steel gears b Applicable     Documents     The     latest     Issue     of Material Specifications shall apply (1) Engineering Process Specifications • Vapor degreasing (item 4, appx B) • Grit blasting (item 3, appx B) (2) Engineering Material Specifications • Molybdenum powder (item 78, appx B) • Solvent, petroleum (Item 5, appx B) (3) ASTM       publications ASTM C-633, Adhesion   or   Cohesive   Strength   of   Flame   -   Sprayed Coatings, Test for c Requirements. (1) Equipment An approved metalizing gun designed to provide automatic gas pressure and powder feed control. (2) Coating   Materials   Coating   materials   shall be   an   approved   nickel-aluminum   composite   powder (item 8, appx B) d Procedure (1) Cleaning WARNING Toxic solvent is used for general cleaning. Illness or skin damage may be caused by prolonged breathing    of    solvent    fumes    or    excessive    skin contact  with  the  liquid  Ensure  there  is  adequate ventilation  and  avoid  open  flame  or  sparks  when using flammable solvent (a)  Steel  Parts  Parts  shall  be  thoroughly cleaned   free   from   dirt,   grease,   oil   or   other   foreign materials  by  vapor  degreasing  (item  4,  appx  B)  or  by washing  In  petroleum  solvent  (item  4,  appx  B)  or  other suitable solvent (2) Masking Parts shall be masked as required to protect areas not designated to be coated Masks may be   steel,   brass,   or   other   suitable   materials   properly protected against adherence by the sprayed coating. (3) Surface Conditioning Grit blast the masked parts  sufficiently  to  remove  all  metallic  luster  Excessive blasting  shall  be  avoided  Grit  blasted  surfaces  shall  be compare  to  Quality  Assurance  standards  and  approved as satisfactory prior to applying the molybdenum coating (a) Care     must     be     taken     to     prevent contamination  of  the  prepared  surfaces  by  contact  or other  means  If  necessary  to  handle  the  prepared  part, clean  lint-free  gloves  (item  6,  appx  B)  must  be  used Parts shall be spray coated as soon as possible but in no case   longer   than   2   hours   after   surfaces   have   been prepared for coating (b) Wipe  grit  blasted  surfaces  with  clean, lint-free  rag  (item  7,  appx  B)  dampened  with  acetone (item  1,  appx  B)  or  other  suitable  solvent  just  prior  to spraying (4) Spray Coating. (a) Place part in fixture designed to permit uniform   coverage   of   areas   designated   to   be   coated Proper  ventilation  is  required  to  remove  over-spray  and non-adherent particles Change 4    14-5