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Qualities & Properties of Muscovite Mica

FED SPEC HHI 536
ASTM D-351
COMMERCIAL CLASS
USES
SCALE OF COMPARATIVE VALUE
QUALITY: SUPERFINE
NMC
V-1
Clear
Geiger-Muller counter windows, Klystron Tubes, Microwave Windows, X-Ray Analysis Instrument, Ultra-thin Mica Windows, Medical, Nuclear, Airborne.
100
NMS
V-2
Clear & Slightly Stained
Large transmitter capacitors, bolometers, metalized resistance cards, special high-quality TV applications, an air regulating diaphragms
65
QUALITY: CAPACITOR QUALITY
NMF
V-3
Fair Stained
Low power loss and high “Q” – for radio & general electronic
45
NMG V-4 Good Stained “Q” slightly lower – for average radio & electronic works Mica Observation Window for Gauge Glass and Oil Burner 32
QUALITY: RADIO TUBE QUALITY
NMSA V-5 Stained A Small capacitors and high-quality radio tube spacers 14
NMSB V-6 Stained B Absolutely clear fuse windows for special applications 12
QUALITY: CLEAR ELECTRIC
NMH V-7 Heavy Stained Fuse windows, heating elements, neon electrodes, thermostat insulators, low-quality tube spacers & for low voltage applications 10
QUALITY: SPOTTED ELECTRIC, STAINED ELECTRIC
NMBS V-10 Black Stained Resistors, motors & appliances (more surface leakage & stains conduct at high voltage) 3
NMBD V-8 Black Dotted 110 / 220-volt insulation, transformer layer insulation, appliances 5
NMBS V-9 Black Spotted Non-conductive dots & spots (small surface leakage in mica) 4s

 

FEDERAL & ASTM Specifications

Federal and ASTM specifications may be used any time, as we are able to furnish a certificate of compliance on the products fabricated.
Following are some of the applicable specifications:

ASTM-D-351-97: VISUAL QUALITY MICA
ASTM-D-748: MICA FOR FIXED CAPACITORS
HH-I-536: VISUAL QUALITY MICA
HH-I-538: ELECTRICAL PASTED MICA

 

MUSCOVITE MICA: PROPERTIES

Optical
Optic axial angle (2V) degrees 38 – 47
Optic plane to plane of symmetry Orientation Perpendicular
Indices of refraction Alfa : 1.552 – 1.570
Beta : 1.582 – 1.607
Gamma : 1.588 – 1.611
Electrical
Dielectric Constant 6.5 – 9
Dielectric Strength ( 1-3 mils thick), Volts/Mil. 6,000 – 3,000
Power Factor at 25°C (77°F) (), percent: 60 cycles : 0.08 – 0.09
1 megacycle : 0.01- 0.02
Resistivity, Ohm-Cm 1012 – 1015
Mechanical
Density Gr./Cu. Cm. : 2.6-3.2
Lb./Cu. Ft. : 160-200
Hardness, Mohs 2.0-3.2
Cleavage Basal, Eminent
Crystal Structure Monoclinic
Max. Temperature with no decomposition 00-500°C
Specific heat (25°C) .206-.209
Thermal Conductivity perpendicular to cleavage Cal./Sq. Cm./Sec./Cm./°C : 16x10-4
B.T.U./Sq. Ft./Hr./I.°F : 4.6
Coefficient of expansion per °C perpendicular to cleavage 20° – 100° C : 15x10-6 – 25x10-6
100° – 300° C : 15x10-6 – 25x10-6
300° – 600° C : 16x10-6 – 36x10-6
Coefficient of expansion per °C parallel to cleavage 0° – 200° C : 8x10-6 – 9x10-6
200° – 500° C : 10x10-6 – 12x10-6
Tensile strength P.S.I. 37,000 – 43,000
Modulus of elasticity 25x106

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