OXIDATION-RESISTANT HIGH-TEMPERATURE PROTECTIVE COATINGS FOR TUNGSTEN

Technical Report · Wed May 01 04:00:00 EDT 1963

OSTI ID:4688268

Nolting, H J; Jefferys, R A

The objective of this program was to develop and apply oxidation resisant high temperature protective coatings on 60 mil tungsten sheet. A series of screening tests, conducted on various tungsten-coating combinations in air at 3300 deg F, determined that three of the coating composites developed exhibited sufficient potential for more extensive study and evaluation. These coatings were: a co-deposited diffusion alloy of silicon and tungsten; a diffusion alloy composite consisting of titainum, zirconium, and silicon-tungsten deposited in successive cycles; and a diffusion alloy composite of titanium, zirconium--boron, silicon--tungsten deposited in successive cycles. The coated tungsten systems, in the oxidized state, were identified as W+(Si- W)--O, W+Ti- Zr-(Si--W)--O and W+Ti-(Zr--B)-- (Si--W)--O. A laboratory scale process for application of each coating system to tungsten by the vacuum pack deposition process was developed and optimized. Oxi-dation characteristics of the coated systems in air under various static and cyclic conditions were determined from 1600 to 3650 deg F. Several hours protection was achieved under cyclic conditions as high as 3550 deg F. Tensile tests on the W+(Si--W)-O and W+Ti-- Zr--(Si-W)--O systems were conducted at regular temperature increments from room temperature to 3300 deg F under various environmental conditions. Tensile properties of uncoated tungsten sheet were determined at the same temperatures under inert atmosphere and vacuum as a basis for comparison. Stress oxidation tests on the W+(Si-W)--O and W+Ti-- Zr- (Si-W)--O systems were conducted in air at 3000, 3200, and 3300 deg F under loads approximating 10 and 20% of the respective system yield strengths. Thermal shock and hot gas erosion tests were also conducted on these coated systems in air at elevated temperatures. Hardness values were determined and reported for the (Si--W)--O and Ti-Zr-- (Si--W)--O coatings in the as coated and exposed conditions. X-ray diffraction patterns of the Ti-- Zr-- (Si-- W)-O coating in the as coated, converted (preoxidized), and exposed conditions were made. Calculated d'' spacing values are reported for the phases present in each condition. X-ray diffraction patterns were also made on the (Si-W)--O coating in the as coated condition and after exposure in air. Construction and design of a high temperature oxidation furnace for coating evaluation tests is described. Operation of the furnace at temperatures of 3000 to 3600 deg F for six week periods without interruption is discussed. (auth)

• Research Organization: Thompson Ramo Wooldridge Inc., Cleveland
• NSA Number: NSA-17-041335
• OSTI ID: 4688268
• Report Number(s): ASD-TDR-63-459; AD-418300
• Country of Publication: United States
• Language: English

Related Subjects

AIR
BORIDES
COATING
CORROSION PROTECTION
DIFFRACTION
DIFFUSION
EROSION
FURNACES
GASES
HARDNESS
HIGH TEMPERATURE
INERT GASES
MATERIALS TESTING
METALS, CERAMICS, AND OTHER MATERIALS
OXIDATION
PHASE DIAGRAMS
PLANNING
PRESSURE
SHEETS
SILICIDES
STABILITY
STRESSES
TENSILE PROPERTIES
THERMAL STRESSES
TITANIUM ALLOYS
TUNGSTEN
TUNGSTEN COMPOUNDS
VACUUM
X RADIATION
ZIRCONIUM ALLOYS