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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, 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 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 : 16×10-4
B.T.U./Sq. Ft./Hr./I.°F : 4.6
Coefficient of expansion per °C perpendicular to cleavage 20° – 100° C : 15×10-6 – 25×10-6
100° – 300° C : 15×10-6 – 25×10-6
300° – 600° C : 16×10-6 – 36×10-6
Coefficient of expansion per °C parallel to cleavage 0° – 200° C : 8×10-6 – 9×10-6
200° – 500° C : 10×10-6 – 12×10-6
Tensile strength P.S.I. 37,000 – 43,000
Modulus of elasticity 25×106

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