Purchase_Description_HVOF_Spray_Powder.pdf

POWDER PURCHASE REQUIREMENTS

22 September 2014

1. Scope. This purchase request covers the purchase of tungsten carbide-cobalt (WC-Co) in the form of powder. This powder is typically used to produce thermal spray coatings to provide wear and fretting resistant surfaces.

2. Application. The end use of the powder is to apply hard face coatings using the HVOF thermal spray process.

3. Nominal Powder Composition. The nominal powder composition is 83% tungsten carbide (WC) and 17% cobalt (Co). See paragraph 6 below for powder composition limits.

4. Method of Manufacture. Powder particles shall be manufactured from feedstock materials using an agglomeration and heat sintering process.

5. Powder Specification. The powder shall meet the technical requirements of SAE AMS

7881, Rev A, “Tungsten Carbide-Cobalt Powder, Agglomerated and Sintered”.

6. Powder Composition Limits. The powder material composition shall conform to the percentages by weight shown in Table 1 of AMS 7881, Rev A.

7. Particle Size Distribution Limits. The powder particle size distribution shall conform to the limits as shown in Tables 2 and 3 of AMS 7881, Rev A. The particle size distribution by percent volume (Table 2) and by percent weight (Table 3) is based on the type of

HVOF spray equipment to be used. See paragraph 9 below.

8. Powder Quality. Powder, as received by the purchaser, shall be thoroughly blended, uniform in color and quality, dry, free flowing and free from foreign materials, clumps and imperfections detrimental to its spraying qualities.

9. Coating Spray Method. The powder particle size distribution shall be produced for spray “Method 2”. Method 2 designates powder materials typically sprayed with a

Praxair/TAFA HVOF thermal spray system. See AMS 7881, Rev A, section 8.3.

10. Powder Testing Requirements. Vendors shall have the capability to perform powder particle size evaluations using a laser light scattering method, i.e., Microtrac analysis, per ASTM B 822 and sieve analysis per ASTM B 214. Powder chemistry evaluations shall be performed by a Nadcap accredited laboratory.

11. Vendor Certifications. Vendors providing powders must be ISO 9001: 2000 and

AS9100B certified.

12. Certification of Powder. A Certificate of Conformance or Certified Materials Report shall be provided with all shipped materials referencing the powder lot, the quantity shipped, powder chemistry, and Microtrac and sieve analysis results. The test lab used for chemical analysis and the lab approval number shall be stated on the Certificate of

Conformance. Reference to material specification AMS 7881, Rev A shall be made on the Certificate of Conformance. The Certificate of Conformance shall be dated and signed by the vendor’s Quality Assurance (QA) manager attesting that shipped materials meet all requirements of the purchase order and material specifications.

13. Coating Specification. The thermal spray powder delivered shall be capable of producing thermal spray coatings that meet the coating requirements of Air Force

Drawing (specification) 200310641, Rev D, “Coatings, Tungsten Carbide on High Strength

Steel, High Velocity Oxygen Fuel Process”. Confirmatory testing may be required.

14. Confirmatory Testing of Powder. The Air Force reserves the right to sample and to perform any confirmatory testing deemed necessary prior to contract award to ensure that the powder conforms to specified requirements and that the powder is capable of producing thermal spray coatings that meet Air Force requirements. See paragraph 13 above for coating requirements.

15. Powder Lots. The total number of powder lots delivered shall be limited to three (3) lots for each purchase order.

16. Powder Quantity. The powder quantity delivered shall not exceed $150,000.00 inclusive of shipping charges.

17. Powder Price. The total powder price (cost per pound) shall be stated by the seller. The powder price shall be inclusive of all shipping charges, packaging, material surcharges, etc.