BISMANOL PERMANENT MAGNETS, EVALUATION AND PROCESSING
Bismanol permanent magnets have been evaluated for stability under various operating conditions. The magnets showed a remarkable flux constancy over a wide temperature range after stabilization at low temperatures. There is some decrease in magnetic flux density at the low temperature; the exact flux loss being dependent on the temperature of stabilization. Because of their high coercive force, the magnets are extremely stable magnetically to shock, vibration, centrifugal force and stray magnetic fields. Except for a tendency to chip, bismanol magnets are sufficiently strong physically for most applications. Unprotected bismanol magnets corrode slightly at ordinary temperatures and humidity, and more rapidly nt 95% humidity. Magnets with applied protective coatings remained stable at room temperatures and moderate humidities for the six- month test period. The processing techniques of bismanol magnets have been improved by eliminating magnetic separation. The new technique consists of the separation of excess bismuth from the melt by hot-pressing prior to pulverization. Present maximum value for the coercive force (Hc) is now 3650 oersteds and 4800 gauss for the residual flux density (Br). Various types of pulverizing equipment were also evaluated with respect to the magnetic properties of the resulting compacts. The methods of determining percentage purity (MnBi content), alignment and effective particle size in bismanol magnets are discussed. (auth)
- Research Organization:
- Naval Ordnance Lab., White Oak, Md.
- NSA Number:
- NSA-13-002985
- OSTI ID:
- 4290472
- Report Number(s):
- NAVORD-2686
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
BISMUTH ALLOYS
CENTRIFUGATION
COATING
COMPACTING
CONFIGURATION
CORROSION
GRAIN SIZE
HOT WORKING
HUMIDITY
IMPACT SHOCK
IMPURITIES
LOSSES
LOW TEMPERATURE
MAGNETIC FIELDS
MAGNETIC PROPERTIES
MAGNETISM
MAGNETS
MANGANESE ALLOYS
MATERIALS TESTING
MELTING
METALLURGY AND CERAMICS
POWDERS
PRESSURE
QUANTITATIVE ANALYSIS
QUANTITY RATIO
SEPARATION PROCESSES
STABILITY
TEMPERATURE
VIBRATIONS