H-91 (1000ºF Fine Grain Alumina Cement Composite Board)

H-91 is an ultra-high temperature, asbestos-free, high density, fiber reinforced composite cement board with a substrate of high alumina cement. This, combined with selected fillers, gives H-91 unsurpassed strength at elevated temperatures up to 1200ºF (649ºC). The material can bcell nameither sodium silicate dipped or silicone impregnated to minimize water absorption making the material suitable for electrical applications, especially in humid conditions.


Density ( lb/ft³ )120
Maximum Operating Temperature ( ºF )1200
Flexural Strength ( psi )4350
Compressive Strength ( psi )16675
Thickness ( in )3
Shear Strength ( psi )3700
Thermal Conductivity at 250ºF ( BTU-in/hr-ft²-ºF )3.4
Volume Resistivity2.55 ohm/in. x 10E10
Arc Resistance ( sec )>360
Water Absorption (After 48 hrs.) ( % )10
Chemical ResistanceFair
Maximum Sheet Size ( in )37 x 49
Continuous Operating Temperature ( ºF )1000


The H-91 properties listed represent typical average values obtained in accordance with accepted test methods and are subject to normal manufacturing variations. They are supplied as a technical service and are subject to change without notice. Check with your supplier to assure current information


It’s unusually high temperature capability and exceptional strength at temperature make H-91 ideal for applications above the 600-900ºF threshold at which most other cement boards fail. Applications include induction furnace insulation, billet heater boxes, molten metal splash guards, and mold base boards. Extremely low thermal conductivity and high compressive strength make H-91 a cost-effective material for high temperature press insulation and hot glass handling parts such as takeouts, deadplates, sweepout pads, and stacker bar insulators. It’s excellent machinability makes H-91 ideal for intricate high temperaturcell namelectrical insulators and other precision machined components.


Foundry Service and Supplies is a full-service fabricator with an unmatched reputation for quick turnaround and competitive pricing. We can easily handle any job for fabricated parts or stock sheets, from high production quantities to prototypes. Our quality and reliability make Foundry Service the best choice for all of your high temperature material requirements.

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