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Black Corundum

Black corundum is a gray‑black crystalline material produced by high‑temperature smelting in an electric arc furnace, using either high‑iron bauxite or high‑aluminum bauxite combined with high‑aluminum iron ore, followed by cooling. It features α‑Al₂O₃ and ferrospinel as the dominant mineral phases and exhibits moderate hardness, excellent self‑sharpening properties, low grinding heat generation, and resistance to surface burn on workpieces.

Keywords:

Yeda New Materials

Category:

Abrasive Series

Contact phone number:

+86-18837126599Manager Li /+86-18837129599Manager Zhang /+86-18837183677Manager Li

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Product Details

  • Product Description
    • Commodity name: Black Corundum

    Black corundum is a gray‑black crystalline material produced by high‑temperature smelting in an electric arc furnace, using either high‑iron bauxite or high‑aluminum bauxite combined with high‑aluminum iron ore, followed by cooling. It features α‑Al₂O₃ and ferrospinel as the dominant mineral phases and exhibits moderate hardness, excellent self‑sharpening properties, low grinding heat generation, and resistance to surface burn on workpieces.

    Microstructure

    TS Series Black Corundum

    ZZ65 Series Black Corundum

    The microstructural image of the TS series black corundum reveals that the α‑Al, which plays the primary role in grinding, … 2 O 3 The crystal size ranges from approximately 50 μm to over 200 μm, with most crystals exhibiting a blocky morphology. They are tightly interconnected and encased within a lower‑strength glassy matrix, closely resembling the microstructure of agglomerated abrasives. As shown in the microstructural image of the ZZ65 series black corundum, the α‑Al phase, which plays the primary role in grinding, … 2 O 3 The crystal size ranges from approximately 100 μm to over 400 μm; however, most crystals are elongated and interconnected, enveloped by substantial glassy matrix. Consequently, both the ZZ65 series and the TS series of black corundum exhibit strong self‑sharpening properties, with the TS series offering even superior self‑sharpening performance and durability.

     

    Product Features

    The microstructure of black corundum crystals determines the product characteristics of black corundum:

    Good self-sharpening: During the grinding process, Al 2 O 3 Particles detach from the lower‑strength SiO2 crystalline regions, forming new cutting edges and thereby exhibiting high self‑sharpening capability.

    Low grinding heat: During the grinding process, Al 2 O 3 The removal of abrasive particles carries away a portion of the heat accumulated at the contact interface between the abrasive and the workpiece. The excellent self‑sharpening property shortens the three stages of grinding—sliding, plowing, and cutting—thereby reducing the generation of grinding heat and minimizing the risk of surface burn on the workpiece.

    High surface finish: During the grinding process, the smaller Al 2 O 3 The particle size results in shallower scratches on the workpiece surface and ensures more uniform groove depths, leading to more consistent light reflection under the same conditions. Consequently, metal surfaces treated with black corundum exhibit a higher degree of surface finish.

     

    Product Specifications

    Physical indicators

    Color: Gray-black;

    Polymorph: Trigonal crystal system;

    Hardness: Vickers hardness: 1950 kg/mm²–2150 kg/mm²,

    　　　Mohs hardness 8–9;

    True density: >3.5 g/cm³;

    Particle size:

    Sand fraction: 3.0–5.0 mm; 1.0–3.0 mm; 1.0–2.0 mm; 0.4–1.0 mm;

    Grain size: 10#–220#, P24–P220

    Microgrit: 230#–1000#; P240–P2000

    It can also be processed according to actual needs.

     

    Chemical indicators

    TS Series

    F220 and coarser: Al2O3 ≥ 80.0%; Fe2O3 ≥ 5.0%; SiO2 ≤ 15.0%; TiO2 2.0–4.0%;

    F220 composition: Al2O3 ≥ 75.0%; Fe2O3 ≥ 5.0%; SiO2 ≤ 20.0%; TiO2 2.0–4.0%;

    ZZ65 Series

    F220 and coarser: Al2O3 ≥ 62.0%; Fe2O3 ≥ 7.0%; SiO2 ≤ 20.0%; TiO2 2.0–4.0%;

    F220 composition: Al2O3 ≥ 60.0%; Fe2O3 ≥ 7.0%; SiO2 ≤ 25.0%; TiO2 2.0–4.0%.

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