ARMY TM 5-6115-612-34 NAVY AG-320B0-MME-000 NOTE No    cleaner    or    solvent    shall    be    used    that    will introduce  excessive  chlorides  or  halides  onto  the surface of titanium pans (b) Aluminum Base Parts or Steel Parts Parts shall be thoroughly cleaned free from dirt,  grease, oil  or  otherforeign  materials  by  vapor  degreasing  or  by washing in petroleum solvent (item 4, appx B) (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   When   section   thickness   or geometry  of  the  part  will  result  In  excessive  distortion due to grit blasting, condition surfaces as follows (a) Titanium  base  parts  Surfaces  shall  be etched  to  roughen  the  surfaces  and  provide  adequate adhesion of the sprayed coating (b) Aluminum   base   alloy   or   steel   parts Surfaces   shall   be   prepared   by   immersion   in   suitable solutions to roughen the surfaces and provide adequate adhesion of the sprayed coating (c) 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 (d) 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 (b)   Preheat   cleaned   and   masked   part   to 175-200o F (79-93° C) (c) Spray  the  nickel-aluminum  composite coating  (item  8,  appx  B)  onto  designated  surfaces  to  a thickness sufficient to meet bond coat re- quirements or, on     salvage     areas,     to     meet     specified     thickness requirements after finish machining. (d) The spray composite must impinge on the surface to be coated at an angle of 75-105 degrees (1.31-1.83 radians). (e) Remove masking in a manner that will avoid damage to the sprayed coating 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   The   following   equipment   is approved for use under requirements of this specification (1) Plasma spray (item 10, appx B) (2) Avco plasma unit D-4 Flame Spray Coating-Nickel Aluminum Composite. a Scope (1) Type This specification covers the procedure    for    flame    spray    deposition    of    a    nickel- aluminum composite coating (item 8, appx B) (2) Application Primarily to detail the procedure for  the  application  of  a  flame-sprayed  nickel-aluminum coating as an undercoat for other sprayed coatings and as a material for salvaging parts by metalizing Change 4    14-3