DEVELOPMENT OF MILITARY COMPONENTS FROM BERYLLIUM BY SLIP CASTING AND POWDER METALLURGY TECHNIQUES. Final Report, September 1959-September 1960

Technical Report · Fri Dec 01 04:00:00 EST 1961

OSTI ID:4804968

The possibility of developing new methods to improve upon the conventional processes for fabricating beryllium metal into finished components by vacuum hot pressing powder and machining blanks thus made to desired configuration and size was studied. The program was primarily devoted to a study of the slip casting of beryllium metal powder and its progressive manipulation into dense structures in the form of small, medium, or large, hollow or solid, complex shapes. During the progress of this work, mechanically cold pressed and vacuum sintered beryllium metal powder was investigated as a means of comparison with slip cast products. A limited amount of work was initiated for the extrusion of slip cast and vacuum sintered preforms of beryllium metal powder. In the beginning of this work it was necessary to purchase and install vacuum sintering furnace equipment with a heating zone 6 inches in diameter by 10 inches high. The space in which this furnace was located with its associated pumping equipment and instrumentation required an enlargement of the laboratory toxic area. While this was being done, a smaller tube furnace was made available by the purchase of additional pumping equipment for preliminary studies. The tentative slip casting procedure for beryllium metal powder requires control of such factors as the particle size of powder; the use of selected organic suspending media, and dispersing and binding agents; the pH of the slip; its viscosity and rheology; the time and tempcrature of drying the green castings and finally; their sintering in vacuum with suitable granular packing material. When these variables were resolved into a tentative procedure, beryllium test pieces were consistently produced with a density greater than 98.5% of relative density and an ultimate bending stress on the order of 58,000 psi and an ASTM grain size of 6 to 7. No material contamination of the sintered beryllium metal apparently resulted from the binder vehicle. However, it is considered possible that the beryllium vapor believed to be present during sintering may react with the packing medium effecting a consequent contamination of the beryllium compact from the products of this reaction, whatever they sumption that the part did not materially change in analysis during sintering. If significant changes in composition did indeed occur, the reported relative densities do nct adequately reflect residual porosity. Micro examination did not, however, reveal any porosity. Cold pressed and vacuum sintered beryllium metal powder packed in aluminum oxide consistently resulted in test pieces of 99.5% of relative density. These generally displayed ultimate bending stresses of 6.0,000 psi and ASTM grain size of 6 to 7. ln two specimens, these cold pressed and sintered pieces proved to be approximately l00% relative density with ultimate bending stress of 90,000 psi and an ASTM grain size of 7 to 8. The extrusion of slip cast and sintered beryllium slugs of various densities was performed satisfactorily. Canning was resorted to only as a precautionary measure for toxicity. The successful extrusions produced under these circumstances were not subjected to either physical or chemical analysis. The slip casting of beryllium preforms for subsequent warm forging without protection is now being investigated. (auth)

• Research Organization: Stevens Inst. of Tech., Hoboken, N.J. Powder Metallurgy Lab.
• DOE Contract Number: AT(29-1)-789
• NSA Number: NSA-16-005691
• OSTI ID: 4804968
• Report Number(s): SCR-306
• Country of Publication: United States
• Language: English

Related Subjects

BERYLLIUM
CASTING
COLD WORKING
CONTAMINATION
DEFORMATION
EXTRUSION
FORGING
FURNACES
GRAIN SIZE
HEATING
HOT WORKING
MECHANICAL PROPERTIES
METALS, CERAMICS, AND OTHER MATERIALS
MICROSCOPY
POROSITY
POWDER METALLURGY
PRESSURE
QUALITATIVE ANALYSIS
SHIELDING
SINTERING
SPACE
TEMPERATURE
TOXICITY
TUBES
VACUUM
VAPORS
VISCOSITY
ZONES