When to use Nextel™ 312 Fibers

3M™ Nextel™ Ceramic Textiles and Composites provide innovative solutions in industries from aerospace to petroleum refining to metal processing. The outstanding thermal protection provided by Nextel™ Fabrics, Tapes and Sleevings allows engineers and manufacturers to handle high temperature applications up to 2500°F (1371°C).
Nextel™ Ceramic Fibers 312 and 440, when converted to fabrics, tapes, sleevings, and paper are used in the aerospace, industrial, automotive, electrical and petrochemical markets as heat shields, curtains, linings, insulation, blankets and seals. Nextel™ Flame Stopping Dot Paper, engineered with Nextel™ Fiber 312, is ideal in applications where both flame barrier properties and light weight are critical.

Nextel™ Composite Fibers

The family of 3M™ Nextel™ Fibers was developed to serve a variety of needs. 3M™ Nextel™ Fibers 312, 440, and 550 are designed for non-structural applications where their primary purpose is to insulate or to act as a flame barrier.  To aid in the selection of the proper fiber for each of these different applications, the fibers are tested in a manner appropriate to their end use.

3M™ Nextel™ 312 Ceramic Fiber Typical Properties

Property	Units	3M™ Nextel™ 312
Use Temperature	—	2200°F
Filament Diameter	mm
Crystal Size	nm	<500
Crystal Type		9Al2O3:2B2O3 + amorph. SiO2
Density	g/cc	2.7
Filament Tensile Strength (51mm gage)	MPa	1700
Filament Tensile Modulus	GPa	150
Surface Area	m2/g	<.2
Composition	wt%	62 Al2O3 24 SiO2 14 B2O3
Thermal Expansion (100-1100°C)	ppm/°C	3 (25-500°C)
Dielectric Constant	(@ 9.375 Ghz)	5.2

3M™ Nextel™ Roving 312 – Typical Properties

Color: White

Roving	Nominal	Yield ± 10%		Breaking Load*
	Filament
	Count	yds/lb	m/kg	lbs	kg
600 denier (67 tex)	400	7420	14950	6	2,7
900 denier (100 tex)	400	4950	9970	7	3,2
1200 denier (133 tex)	750	3720	7490	12	5,4
1800 denier (200 tex)	750	2480	4990	14	6,4
3600 denier (400 tex)	1375	1240	2500	24	10,9

3M™ Nextel™ Plied Yarn 312 – Typical Properties

Color: White

Yarn	Ends	Diameter in mm		Yield ± 10% yds/lb             m/kg		Breaking Load* lbs         kg
600 denier (67 tex) 2.7 Twists/inch (106 Twists/m)**
1/2	2	0.007	0,18	3590	7240	14	6,4
900 denier (100 tex) 2.7 Twists/inch (106 Twists/m)**
1/2	2	0.01	0,25	2390	4820	19	8,6
1/3	3	0.014	0,36	1580	3190	29	13,2
2/2	4	0.016	0,41	1180	2380	35	15,9
1/5	5	0.019	0,48	950	1920	43	19,5
2/3	6	0.024	0,61	780	1570	53	24,0
3/4	12	0.034	0,86	390	790	99	44,9
4/5	20	0.052	1,32	230	460	150	68,0
3/8	24	0.054	1,37	195	390	160	72,6
1800 denier (200 tex) 2.7 Twists/inch (106 Twists/m)**
1/2	2	0.016	0,41	1190	2400	32	14,5
1/3	3	0.021	0,53	790	1590	45	20,4
1/4	4	0.026	0,66	590	1190	63	28,6
2/2	4	0.028	0,71	590	1190	57	25,9
2/3	6	0.034	0,86	390	790	89	40,4
2/5	10	0.05	1,27	230	460	150	68,0
2/6	12	0.054	1,37	195	390	145	65,8

Note:  All yields are based upon sized rovings and yarns.  The allowable range in add-ons for sizing is 1.1 to 3.0% by weight.  The allowable tolerance on final twist is ± 30%.
*  Tested at room temperature.
**  The allowable tolerance on final twist is ± 30%.  Other twist levels available.

3M™ Nextel™ 312 Roving Strength Maximum Temperature Limit

	Roving Strength
Fiber	Maximum
	Temperature Limit
Nextel™ 312

* Strain rate = 12.5 mm/min

Fiber Weight Loss Nextel™ 312 Ceramic Fiber Roving

Roving samples were subjected to 2192°F (1200°C) for fifteen hours. Fibers were weighed before and after the fifteen hour exposure in order to determine weight loss. The fiber evolves B2O3 at temperatures greater than 2012°F (1100°C).

Fiber	Weight Loss %
312

Shrinkage on Nextel™ 312 Fiber

Roving samples were held at each temperature for fifteen hours. After that time they were measured for shrinkage. All fiber compositions showed less than three percent shrinkage after fifteen hours at 2372ýF (1300ýC). Fiber compositions other than Nextel™ Roving 312 showed shrinkage of less than 1.5% at these conditions.

Nextel™ Ceramic Fiber 312 Moisture Absorption

The 3M™ Nextel™ Ceramic Fibers 312 absorb very little moisture due to their smooth, non-porous surface. Fibers exposed to 100% relative humidity for several hours at room temperature had 0.08% weight gain.

Electrical Insulation Resistance on 3M™ Nextel™ Braided Sleeving 312 (unsized)

Insulation resistance of 3M™ Nextel™ Braids on Type K thermocouple wire was measured as the temperature was increased from ambient to over 1832°F (1000°C). With 12 inch (30,5 cm) sections exposed to the test temperature, the remainder of the 18 inch (45,7 cm) thermocouple specimen extended through the oven wall and was connected to an ohmmeter. All wires were open-ended.  A typical curve of insulation resistance as a function of temperature is shown in the figure below for thermocouple wires insulated with unsized yarn.  The values of insulation resistance will change depending on thickness, length of thermocouple wire and braid construction.

IR Absorbance and Transmittance 3M™  Nextel™ Ceramic Fiber 312

A small flake of alumina-boria-silica (3:1:2) fired to 1742 F (950 C) was used to  determine the transmittance and absorbance of 3M™ Nextel™ Ceramic Fiber 312 in the infrared region. The thickness of the flake was determined from the interference pattern to be 22.4 m thick. The following graph shows that in the shortwave number region (4000-3000 cm-1) the transmission loss is small and appears essentially due to reflection. Weak absorption shows between 2700 and 1700 cm-1. Beyond 1700 cm-1 absorption becomes strong and finally complete beyond 1400 cm-1. Absorbance can be calculated from the relationship A=log10 (100)/(%T).

Cryogenic Testing on 3M™ Nextel™ Woven Tape 312

Five samples of 3M™ Nextel™ Woven Tape 312 1 inch (2,54 cm) wide were cut to 6 inch (15,2 cm) lengths for testing in liquid nitrogen.
Samples were heat cleaned at 1472degF (800degC) for one hour to remove the sizing before testing.
Samples were placed in liquid nitrogen to soak for three minutes. Samples were then removed and tested for strength retention.
A second set of five samples was dipped into liquid nitrogen ten times and then tested for strength retention.

	Retained Strength
Sample	Soaked 3 Minutes in N2	Dipped 10 Times in N2
3M™ Nextel™ Tape 312	127%	81%

 

Radiation Resistance & Microwave Measurement - 3M™ Nextel™ Ceramic Fiber 312 Radiation Resistance

Exposure to radiation from a Cobalt 60 source did no noticeable damage to the 3M™ Nextel™ Fiber 312. A total of 1 x 107 rads at an exposure rate of 2.1 x 10 5 rads/hour did not change the tensile strength of the fibers, yarns or fabrics made from the fibers.

Microwave Measurements

Power Transmission and Reflection for 3M™ Nextel™ Fabric panels 18 inch x 18 inch (45.7 cm x 45.7 cm) at 10 GHz.

Fabric	Transmission*	Reflection**	Transmission*	Reflection**
Specimen	5	10	5	10
	Layers	Layers	Layers	Layers
AF-30	96.50%	97.80%	7%	0.45%
BF-30	94.70%	96.70%	7%	0.14%

*Sample held with styrofoam panels, angles of incidence 0°.
**Sample uncompressed, angle of incidence 10°. Compared to copper plate with perpendicular polarization.

3M™ Nextel™ Woven Fabric 312 – Thermal Optical Properties*

The optical properties of fibers on the exterior of the space craft controls the amount of solar heating that will occur in orbit. For instance, a low absorptivity would be desired if one were designing components for a spacecraft mission. This would reflect most of the sun’s energy and protect the craft and the instruments from high temperatures.
Optical measurements were made on 3M™ Nextel™ Woven Fabrics 312 using a Gler Dunkle DB-100 Emissometer and MS-251 Solar Reflectometer machines. The average absorptance () and emittance () are as follows:

Material	Absorptivity	Emissivity
312	0.14	0.88

NASA Nonmetallic Material Testing*

Flammability, Toxicity and Thermal Vacuum Stability testing on 3M™ Nextel™ Woven Fabrics was performed using procedures specified in NHB 8060.1B and SP-R-0022A.
Flammability: Passed test in 30% oxygen and 10 psia environment.
Toxicity: Passed Test.
Thermal Vacuum Stability: Heat cleaned fabric passed test. Sized 3M™ Nextel™ Fabric outgassed volatile condensable materials of 0.15%, which exceeded the required limit of 0.1 weight %.
*Courtesy-NASA

Back to 3M™ Nextel™ Overview

Further information on 3M™ Nextel™ 312 Ceramic Textiles

• Nextel™ 312 MSDS
• Nextel™ 312 Tape Products
• Nextel™ 312 Fiber Data

Further information on other 3M™ Nextel™ Ceramic Textiles

• Click for Nextel™ 440
• Click for Nextel™ 550
• Click for Nextel™ 610
• Click for Nextel™ 720

 

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