Lava (Grade "A")

Grade A Lava is a machinable ceramic that exhibits good electrical and heat resistance. Excellent thermal shock properties allow it to be used in applications where long term thermal cycling is a consideration. Low thermal conductivity is also a highlight of this material.

Lava is a natural, mined stone known as hydrous aluminum silicate and sometimes called Wonder Stone. This machineable ceramic material has many applications in both the unfired and fully fired state. We offer unfired feedstock in block, rod, plate or bar form and also provide fired, finished components manufactured to your technical specifications.

Unfired lava is a free machining material, easily worked with normal tooling and methods. It can be milled, turned, drilled, tapped and threaded. Commonly used as a prototyping material and for fixturing used in high temperature applications.

Unfired machined parts are hardened by kiln firing and once fired they are only workable by diamond grinding. This material has a predictable expansion of about 2% which must be taken into consideration while machining if the part is to be fired. Lava is capable of maintaining very close tolerances from the unfired to fired state, often eliminating the need for additional after firing grinding.

Fully fired lava becomes very hard and has superb thermal shock and excellent electrical properties. It is well suited to applications demanding repeated thermal cycling.

Lava is a natural material with a range of color and texture. Texture ranges from smooth/glossy to rough/dull. Color varies from light tan to dark black. Texture and color can be uniform or mottled in the same part or batch of parts. This variation is to be expected as a normal characteristic of the material.

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Materials Property Chart
  Lava
  Property ASTM Method Units Lava Grade A Fired
General Color -- -- Gray-Tan
Gas Permeability -- atms-cc/sec Porous
Water Absorption C 20-97 % 3
Mechanical Density C 20-97 g/cc 2.30
Hardness Vickers 500gm GPa (kg/mm2) 4.4 (450)
Hardness -- R45N 42
Flexural Strength (MOR)
(3 point) @ RT
F417-87 MPa (psi x 103 69 (10)
Tensile Strength @ RT -- MPa (psi x 103) 21 (3)
Compressive Strength @ RT -- MPa (psi x 103) 172 (25)
Thermal C.T.E. 25 - 100° C C 372-96 x 10-6/C 2.9
C.T.E. 25 - 300° C C 372-96 x 10-6/C 3.3
C.T.E. 25 - 600° C C 372-96 x 10-6/C 3.6
Thermal Conductivity @ RT C 408 W/m K 2
Max Use Temp -- Farenheit (°F) 2000
-- Celsius (°C) 1100

Electrical

Dielectric Strength (.125" Thick) D 149-97A V/mil

100

Dielectric Constant @ 1 MHz D 150-98 --

5.3

Note: The information in this data sheet is for design guidance only. STC does not warrant this data as absolute values. Forming methods and specific geometry could affect properties. Slight adjustments can be made to some of the properties to accommodate specific customer requirements. Most of the dense materials in the table are resistant to mechanical erosion and chemical attack. STC has performed ASTM testing qualification for certain compositions, in accordance with ASTM D2442. Please consult our technical staff for appropriate material and specific test results.