TASK 70-49-10-340-011
1 . General.
A.This procedure covers application of the powder form by plasma spraying.
B.Nickel-Aluminum is used either to form a bond with various top coat systems, or for dimensional restoration.
NOTE:
If Nickel-Aluminum is used as a bond coat, tensile bond strength requirement will not be applicable unless otherwise specified in the Engine/Shop Manual.
NOTE:
Nickel-Aluminum may also be applied as wire by flame spraying per TASK 70-49-11-340-012, Thermal Spraying Nickel-Aluminum (Wire), or by electric arc spraying per TASK 70-49-38-340-037, Electric Arc Wire Spraying Nickel-Aluminum (Wire). Those two procedures are acceptable alternatives.
2 . Equipment.
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C.Refer to TASK 70-49-00-340-001, Thermal Spraying.
3 . Material.
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D.Nickel-Aluminum Composite Powder, Class A C07-016  .
E.Nickel-Aluminum Pre-Alloyed Powder, Class B C07-016  .
4 . Spraying Parameters.
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F.Starting parameter sets will be listed in the spray equipment manuals or are readily available from the spray equipment manufacturers or powder suppliers. Modifications may be necessary for your location and product application. See sprayability testing per TASK 70-49-00-340-001, Thermal Spraying, and TASK 70-70-00-700-001, Testing and Quality Analysis. When the final spray parameter settings are developed, all values should be recorded to ensure consistent achievement of high quality coatings.
5 . Quality Assurance.
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G.Thickness.
Measure the coating thickness using a standard flat-anvil-and-spindle micrometer. The measurement may be made on either a coated production part or on a flat test specimen having a thickness of at least 0.060 inch (1.52 mm). Determine coating thickness to the nearest 0.001 inch (0.03 mm) at three different locations.
H.Appearance.
Visual examination of the coating shall be in accordance with the following:
(1)Adhesion.
The coating shall exhibit no spalling or lifting.
(2)Coverage.
The coating shall exhibit complete, uniform coverage in those areas specified for coating in the Engine/Shop Manual. Coating is not permissible in areas other than those specified.
(3)Surface condition.
The coating shall be uniform and free from cracks, blisters, spatter, chipping, and flaking.
I.Coating Microstructure.
Test specimens shall be prepared for microscopic examination, and evaluated in accordance with TASK 70-71-04-700-005, Metallographic Evaluation of Thermal Spray Coatings. Metallographic examination of the prepared specimen shall be made for uniformity of coating, as well as for the following other conditions:
(1)Delaminations.
The coating shall be free of delaminations as defined for metallic coatings in TASK 70-71-04-700-005, Metallographic Evaluation of Thermal Spray Coatings.
(2)Integrity.
The coating shall show acceptable integrity as defined in TASK 70-71-04-700-005, Metallographic Evaluation of Thermal Spray Coatings.
(3)Interface Separation.
The coating shall be free of interface separations as defined in TASK 70-71-04-700-005, Metallographic Evaluation of Thermal Spray Coatings.
(4)Transverse Cracks.
The coating shall be free of transverse cracks as defined for metallic coatings in TASK 70-71-04-700-005, Metallographic Evaluation of Thermal Spray Coatings.
(5)Interface Contamination.
Interface contamination in the coating shall be identified as defined in TASK 70-71-04-700-005, Metallographic Evaluation of Thermal Spray Coatings, and then rated per the guidelines of Table 1.
(6)Oxides and Oxide Clusters.
Oxides in the coating shall be identified as defined in TASK 70-71-04-700-005, Metallographic Evaluation of Thermal Spray Coatings, and then rated as described in the guidelines of Table 1. The coating shall be free of oxide clusters as defined in TASK 70-71-04-700-005, Metallographic Evaluation of Thermal Spray Coatings. Oxides shall be uniformly distributed.
(7)Porosity.
Porosity in the coating shall be classified for size as defined in TASK 70-71-04-700-005, Metallographic Evaluation of Thermal Spray Coatings, and then rated per the guidelines of Table 1. Porosity shall be uniformly distributed.
J.Tensile.
Tensile specimens shall be prepared for tensile bond testing and evaluated in accordance with TASK 70-71-01-700-002, Bond Strength Tensile Testing of Thermal Spray Coatings. If this coating is applied in a thickness range up to 0.015 inches (0.38 mm), the tensile bond strength for this coating at room temperature shall average 5,000 psi (34.5 MPa), minimum. If this coating is applied in a thickness range greater than 0.015 inches (0.38 mm), the tensile bond strength for this coating at room temperature shall average 4,000 psi (27.6 MPa), minimum.
K.Bend Test.
The technical requirement for this test has been deleted and no longer needs to be performed when specified in the Engine/Shop Manual.
 
Acceptance Limits for Thermal Spray - Table 1
 
Feature
Acceptance Criteria
Rating Photograph
Task
Comments
 
Porosity
Less than or equal to V-1
Figure 25
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None
 
Oxides
Oxides shall be uniformly distrib-uted. Reject cluster oxides as shown in Figure 6 view X-3.
Figure 6
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None
 
Oxide Clusters
None allowed
No figure for rating
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See definition for ratable size
 
Interface Contamina-tion
Less than or equal to I-2
Figure 7
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None.
 
Interface Separations
None allowed
No figure for rating
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See definition for ratable size
 
Transverse Cracks
None allowed
No figure for rating
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See definition for ratable size
 
Delamina-tions
None allowed
No figure for rating
TASK 70-71-04-700-005
See definition for ratable size