Accession Number:

ADA393621

Title:

High-Rate Sputter-Deposited Tantalum Coatings on a Steel Liner for Wear and Erosion Mitigation

Descriptive Note:

Final rept.,

Corporate Author:

ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS

Report Date:

2001-08-01

Pagination or Media Count:

29.0

Abstract:

A prototype, rifled steel liner of 20-min inside diameter was coated with -50 to 125 micronmeter tantalum at -22.6 micronmeterhour in krypton gas using a triode-sputter system. It was test fired with l5OO rounds for the mitigation of high-temperature and pressure wear and erosion. Growth surface analysis showed predominately alpha-phase and minimal beta-phase surface tantalum. Area detector images showed near random, slight preferred 211 crystalline orientation. X-ray diffraction revealed a thin layer of surface zinc oxide and copper firing debris on the coating surface. Compressive surface residual stress peaked near the center of the tube. Photomicrograph metallurgical examination showed general good adhesion in major parts of the bulk coatings, along with a thin layer of beta-phase nucleation, and alpha-phase or mixed alpha- and beta-phase grain growth. There was excellent behavior in soft and ductile a-tantalum areas, but cracking and disbonding occurred in beta-tantalum areas. Coating liftoff and coating loss occurred most frequently in landgroove transition and land areas, less in groove areas. Near the breech end where no coating was sputtered, the steel substrate suffered extensive cracking and environmentally-assisted heat damages.

Subject Categories:

  • Coatings, Colorants and Finishes
  • Properties of Metals and Alloys
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE