Corrosion Testing of HVOF Thermal Spray Coatings porosity

Document Sample
Corrosion Testing of HVOF Thermal Spray Coatings porosity Powered By Docstoc
					Corrosion Testing of HVOF
Thermal Spray Coatings
  By:
  Stephen P. Gaydos
  Boeing – St. Louis
  20 February 2002

                 1
Chrome Plate Baseline
  #1 Problem is QQ-C-320
     Has No Corrosion Resistance Requirement
        Ferroxyl Porosity Test (Allows 15 pits/150 sq.in.)

  Why No Corrosion Testing In QQ-C-320?
     Chrome Plate Contains Cracks and Porosity and
      Could Not Pass a Corrosion Test
     Chrome Plate Appears to Work O.K. in Severe
      Service Environments So Corrosion Testing Never
      Added as Requirement


                              2                               2
HVOF Corrosion Testing

  What Criteria Do You Use for HVOF?
     Can’t Use QQ-C-320 So Create Your Own
       Put in Salt Spray and Look for Red Rust (Most
        Popular Criteria Being Used)
            Tells You if You Have Base Metal Corrosion
       Put in Salt Spray and Look For Any Signs of
        Corrosion – Base Metal or Coating
            Currently Under Investigation
       Conduct Electrochemical Testing
            Potentiodynamic, Potentiostatic, EIS, etc.


                               3                          3
HVOF Sample Prep
 1018 Steel - 1” O.D. Bar
 Grit Blast
 Apply per BAC 5851
    St. Louis Metallizing
    SM Diamond Jet & TAFA JP5000
 Powders - WC-17Co
      SM 2005 (Normal) & 2006 (Fine)
      TAFA 1343VM (Normal) & 1343VF (Fine)


                        4                     4
HVOF Sample Prep (Cont.)
 Powders - WC-10Co-4Cr
      SM 5847
      TAFA 1350VM
 Thickness 3 to 5 mils
 As Sprayed and Ground to 8 micro inch
 Sealers
    Metco Seal AP and URS


                     5                   5
Chrome Plate Prep
 1018 Steel - 1” O.D. Bar
 Grit Blast
 Chrome Plate per PS 13102 (QQ-C-320)
     2 to 3 mils thick
     Two Different Plating Vendors Used
     Optional Ni Underplate Applied At 1.5 mils
 As Plated (No Grinding)
 Sealers
     Metco Seal AP or URS
     IMPCO RC-80 per PS 11501

                        6                          6
HVOF Specimen Prep




            7        7
HVOF Test Specimens (Before)




   DJ/5847/8uin       TAFA/1350VM/8uin
                  8                      8
Corrosion Tests
  Salt Spray Tests
     ASTM B117 - Neutral Salt Spray
     ASTM G85 - SO2 Salt Spray
  Electrochemical Tests
     Determine Corrosion Rates (mils per year)
        Potentiodynamic
        EIS



                           9                  9
Salt Spray Test Results




             10
    5% NaCl Salt Spray Results for Chrome Plating



Cr Plate                      Cr Plate
2 Days =                       2 Weeks =




Cr* Plate                      Cr* Plate
1 Week =                       2 Weeks =



*Cr Plate Vendor #2      11                     11
      SO2 Salt Spray Results for Chrome Plating




     2 Days for Cr Plate        1 Week for Cr* Plate


*Cr Plate Vendor #2
                           12                          12
         Salt Spray Results for Ni/Cr Plating




30 Days in 5% NaCl Salt Spray        30 Days in SO2/NaCl Salt Spray

                                13                               13
       5% NaCl Salt Spray Results for HVOF Coatings


4 Week
Exposure =
For WC-Co

         TAFA/1343VM/8uin   TAFA/1343VF/8uin   DJ/2005/8uin   DJ/2006/8uin




4 Week
Exposure For =
WC-Co-Cr


               TAFA/1350VM/8uin                DJ/5847/8uin
                                    14                               14
    SO2 Salt Spray Results for HVOF Coatings


Two Day
Exposure =
For WC-Co


          TAFA/1343VM/8uin   TAFA/1343VF/8uin   DJ/2005/8uin   DJ/2006/8uin




One Week
Exposure For =
WC-Co-Cr

                 TAFA/1350VM/8uin                     DJ/5847/8uin

                               15                                    15
Electrochemical Test Results




             16
17   17
*Cr Plate Vendor #2   18   18
*Cr Plate Vendor #2   19   19
*Different Cr Plate Source   20   20
Conclusions
  Not All Chrome Plate Behaves The
 Same In Corrosion Tests
  Sealing Helps Chrome Plate But Does
 Not Appear to Help HVOF Coatings
  HVOF WC-10Co-4Cr Has Better
 Corrosion Resistance Than WC-17Co
  Nickel Underplate With Chrome Plating
 Has Superior Corrosion Resistance

                   21                     21

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:84
posted:5/15/2011
language:English
pages:21