International Hydrolytics Ltd.

Thermal Physical Properties

IHL is pursuing an aggressive program of materials testing and data acquisition. This program includes research into a broad spectrum of new matrix configurations, fabrication methods, property variation, and additive compatibility and effect. Composite matrix materials and their respective properties depend almost entirely upon the density, configuration, additives or doping agents, and other incorporated materials, laminates, etc. Structural integrity and mechanical strength can be significantly enhanced by the addition of suitable fibers, and bulk properties of composite structures and laminates offer a new frontier in product technology. Many important properties may not have been determined, or are presently undergoing evaluation in conjunction with modifications in the materials to achieve the desired effect. The best method to follow is to inquire into the feasibility of a particular property being achieved with currently available techniques and materials. Some data of interest is provided in the following as a guide to potential applications.

1. Density.

Normal densities of H-CORE range from 240 kg.m-3 (15 lb/ft3) to 1,920 kg.m-3 (120 lb/ft3). Lower effective densities can be achieved with either a variety of petrol-chemical dispersed phase additives or compatible foaming agents.

2. Thermal Conductivity.

The thermal conductivity of AHC is generally proportional to the density of the matrix. A normal value measured at 100 C varies in the range .051-.092 W.m-1*C-1 (0.354-0.638 Btu* in/ft2/hr/*F). The associated “R values” (reciprocal heat transfer coefficient) are 2.82 to 1.57 per inch of thickness respectively, values which are comparable to mineral fiber acoustical tile.

3. Compressive Yield Strength.

Yield strength is also proportional to matrix density. Oven dried 449 kg.m-3 (28 lb/ft3) density material has a compressive yield of 1846 kN/n2 (268 psi). Oven dried after 72 hour water inversion decreases yield to approximately 1736 kN .m-2 (252 psi). Normal compressive yield for undried material is in the range of 772-1123 kN.m-2 (112-163 psi); however, when laminated with 20 ga. face sheets of aluminum, or similar material, compressive strengths increase by a factor of over 160 to 2.59 x 107 N.m-2 (3.76 kpsi) with associated flexural strength of 5.76 x 107 N.m-2 (8.36 kpsi).

4. Tensile Strength (non-reinforced midrange densities).

Normal loading: 172.9 kN.m-2 (25.1 psi)

Transverse loading: 86 kN.m-2 (12.5 psi)

Shear: 144 kN.m-2 (28.9 psi)

5. Modulus of Rigidity.

4.08 x 10 6 N.m-2 (592 psi)

6. Modulus of Elasticity.

1.3 x 10 6 N.m-2 (189.4 psi)

7. 4.2 mm Screw Extraction Pull Strength

498-756 N (112-170lb.)

8. Acoustic Attenuation.

Preliminary testing in the frequency band greater than 10 KHz indicates attenuations of 30-80 dB.c-1 are possible depending upon dispersed phase particle size distribution. Reflection albedos are also under present investigation with various surface geometries.

9. Maximum or Limiting Working Temperatures.

High temperature faces suffer some vitrification at the inter-face, which changes the properties somewhat. Thus limiting working temperatures for unlaminated core material depends upon board thickness. Recommended temperature range for thicknesses less than 38 mm (1.5 in.) is 200-900*C. For thickness greater than 38 mm the range is increased to 350-1050 *C. Permanent shrinkage due to vitrification at 843*C (1550 *F) is 1.5%.

10. Heat Stability.

Coefficient of thermal expansion (20-800*C): 3.75 x 10-6 *C-1

Melting point: = 1350*C (2462 * F)

11. Moisture Stability.

Hygroscopicity: 3.9% weight gain at 100 % RH for 72 hours

Linear dimensions: +0.05 % at 35 *C (95 *F) at 95 % RH

Moisture loss: 5 % by weight (20-105 *C)

Solubility in water: (1 % by weight after 3 weeks immersion)

Capillarity: no observed effects

12. Chemical Effects.

Essentially chemically inert and insoluble in most acids and bases. It resists all normal pollutants, atmospheric, or otherwise.

13. Biological Effects.

Contains no asbestos, toxic compounds, or carcinogens, and it will not support any form

of biological growth, bacterial or viral. In the undoped condition it has no volatile residues and is

smokeless, odorless, non-irritating, rot-proof, and vermin proof.

14. Color.

Pearl white in the unmodified state. It can be easily colored with pigments or sprayed with conventions paints and other surface

treatment compounds.

15. Photo Resistance.

Contains no organic compounds and is therefore impervious to excess ultraviolet and infrared radiation.

16. Electrical Insulation Properties.

The dielectric strength, or maximum electrical stress, is a function of the composite material density and aggregate size. As a glass-air hybrid composite, this material is expected to demonstrate exceptional characteristics. Complex dielectric constant microwave measurements in the S, C, and X band (68 cm - 2.5 cm wavelength) show a loss tangent which is very nearly zero, showing great promise as an electromagnetically transparent material.

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