Applications of platelet alumina in the glass industry

Applications of platelet alumina in the glass industry

Platelet alumina consists of flat α-Al₂O₃ single crystals with smooth surfaces, rounded edges, and a high aspect ratio, distinguishing it from ordinary spherical or granular alumina. In the glass industry, it is primarily used as an abrasive for precision grinding and polishing, as a functional filler and crystal phase modifier, and as a substrate for optical coatings on glass surfaces.

I. Platelet alumina as a precision polishing abrasive for deep glass processing

1. Applicable glass 

1) Cover glass for consumer electronics: tempered high-alumina-silicon cover glass for mobile phones, tablets, and watches; 3D curved glass; camera protective lenses.

2) Optical glass: spectacle lenses, prisms, lenses, infrared optical windows, quartz glass, crystal glass;

3) Display substrate glass: TFT-LCD liquid crystal substrate, display glass shell, LCD ultra-thin flat glass;

4) Special glass: borosilicate heat-resistant glass, piezoelectric crystal glass, aerospace observation window glass.

2. Unique advantages of platelet alumina

1. Low scratches, ultra-mirror finish: Flat particles are laid flat and adhere to the glass surface, mainly using sliding grinding. The cutting force is uniform, with few sharp edges and corners, and very few deep scratches are produced. The surface roughness of the glass can be reduced to the nanometer level, which greatly improves the pass rate. It makes up for the shortcomings of insufficient grinding force of cerium oxide polishing powder and is often used in combination with cerium oxide for fine polishing.

2. High grinding efficiency, long powder life:particles are not easily broken, good cutting stability, can be used for rough grinding to remove tool marks, and can also be used for final polishing; good suspension, uniform slurry dispersion, suitable for fully automatic continuous polishing production lines.

3. Hardness matching glass material: Mohs hardness 9, which can quickly remove surface defects of silicate glass without excessively etching the glass surface, making it particularly suitable for processing ultra-thin substrates and thin cover glass.

3. Process Scenarios

Rough grinding / fine grinding: double-sided grinding of flat glass, CNC finishing of curved glass;

Chemical mechanical polishing (CMP): Ultraplanarization treatment of liquid crystal substrates and optical lenses

Final polishing: Matte/glossy polishing of mobile phone glass back covers and lens elements.

II. Modification of Special Glass Body Using platelet Alumina as Raw Material

1. Application of platelet alumina in aluminosilicate cover glass and high-alumina glass

Platelet alumina is used as the raw material for glass melting

1. Platelet alumina grains melt at a more uniform rate, reducing glass melt streaks, bubbles, and crystallization defects, thus improving glass homogeneity;

2. Platelet alumina acts as a network intermediate, forming aluminum-oxygen tetrahedra, which significantly improves the hardness, bending strength, and chemical corrosion resistance of glass, and enhances the chemical tempering effect;

3. Platelet alumina reduces the coefficient of thermal expansion of glass, increases the strain point, and improves thermal shock resistance, making it suitable for high-end cover glass formulations.

2. Platelet alumina as a nucleating agent and filler for microcrystalline glass (glass-ceramic)

Platelet alumina can be used as a plate-like crystal phase inducer: it induces the formation of plate-like crystals inside glass-ceramics, thereby toughening the glass-ceramics and improving their bending strength and wear resistance. It is used in architectural decorative glass-ceramics and electronic packaging glass-ceramics.

3. Platelet alumina for glass surface optical coating and pearlescent effect substrate

1. Glass pearlescent decorative coating  Highly flat and defect-free platelet alumina is used as the base material of pearlescent pigments. It is coated with metal oxide and then coated on the surface of decorative glass and art glass to form a high-gloss pearlescent and phantom interference effect. It can replace natural mica flakes. It is resistant to high temperatures, acids and alkali, and will not fade after long-term use.

2. Glass anti-glare and diffuse reflection coating filler: Platelet alumina flake particles are arranged in parallel to form a uniform microstructure, enabling tempered glass and shop window glass to achieve soft diffuse reflection, reduce mirror glare, and improve the coating’s wear resistance.

IV. Auxiliary materials for glass production – Platelet alumina

1. Bonded abrasive fillers for glass edging and drilling: Resin grinding wheels made of platelet alumina are less prone to chipping when grinding glass edges;

2. Glass cleaning and grinding media: Platelet alumina finely graded flat micro powder is used for ultrasonic grinding and cleaning to remove dust and tiny stains from the glass surface.

V. Specifications of Platelet Alumina Produced by Haixu Abrasives

Chemical composition

Physical properties

PSD(Particle Size Distribution)