Metal Silicon Powder

Metal silicon powder is simply silicon ingots ground into powder. Customers who buy this powder generally fall into two categories:

First category: For metallurgical use (steel deoxidation, aluminum alloys, casting inoculants). These customers don't require extremely high purity (97%-99%), but they are particular about particle size-too fine and it smokes and is wasteful; too coarse and it won't dissolve properly.

Second category: For chemical use (organosilicon monomers, silanes, silica). These customers require both high purity and high size (above 99%, above 200 mesh) because impurities will poison the catalyst in chemical reactions.

 Industrial grade (purity 97%-99%)

Uses: Steel deoxidation, aluminum alloy batching, casting inoculants.

Size selection: 50-100 mesh is most commonly used. This size dissolves quickly in a ladle without smoking or being absorbed like powder.

Purity selection: 97% or 553 is sufficient; using 441 is wasteful. This is because metallurgy primarily utilizes silicon's deoxidation and alloying properties, making it less sensitive to impurities.

 Chemical grade (purity 99% or higher)

Applications: Organosilicon monomer synthesis (for silicone oils and rubber), silane gas, silica.

Size selection: 200-500 mesh; finer particles result in faster reactions. For fluidized bed reactors in organosilicon production, 325 mesh is the mainstream.

Purity selection: 441, 3303, 2202; higher purity reduces the risk of catalyst poisoning. For high-end organosilicon production, even specialized powders with purity exceeding 99.9% are used.

1. Industrial-Grade Metallic Silicon Powder (Purity 97.0%-99.0%)

Core Composition: Si 97.0%-99.0%, Impurities: Fe 0.5%-1.5%, Al 0.3%-0.8%, Ca 0.2%-0.5%
Size Range: 50-300 mesh (80-200 mesh commonly used);
Typical Applications: Metallurgical deoxidizer (steel, cast iron), aluminum/magnesium alloy additive (to improve alloy strength and corrosion resistance), refractory material (compounded with Al₂O₃ and MgO to improve high-temperature resistance);
Features: Low cost, easy processing, low impurity control requirements, and emphasis on functionality (such as deoxidation and alloying) rather than high precision.

2. Chemical-grade metallic silicon powder (purity 99.0%-99.5%)

Core composition: Si 99.0%-99.5%, impurities: Fe ≤ 0.3%, Al ≤ 0.2%, Ca ≤ 0.1%
Size range: 200-800 mesh (primarily fine powder, reactivity required);
Typical applications: Chemical synthesis raw materials (for the preparation of silane SiH₄, silica SiO₂, and organosilicon monomers such as methylchlorosilane); welding materials (as a component of electrode coatings to improve weld toughness);
Features: Requires controlled impurities (especially Ca to prevent reaction with chemical raw materials to form impurity salts); emphasizes "high reactivity"; relies on fine particle size to maximize specific surface area.

1. Metallurgy: Its core functions are deoxidation and alloying.

Steel deoxidation:

During the steelmaking process, 50-100 mesh industrial-grade silicon fume is added to the molten steel. Silicon reacts with oxygen in the molten steel to form SiO₂ (which floats on the surface of the molten steel to form slag), reducing the oxygen content in the steel and preventing hot brittleness. Silicon also improves the strength and wear resistance of the steel and is commonly used in spring steel and bearing steel.

Aluminum alloy additive:

80-200 mesh industrial-grade silicon fume is added to the molten aluminum alloy. Silicon reacts with aluminum to form an Al-Si alloy, improving the alloy's corrosion resistance, casting properties (lowering the melting point), and hardness. It is widely used in automotive wheels (ADC12 aluminum alloy, containing 9.5%-12% Si) and aluminum alloy profiles.

Cast iron inoculant:

Adding a small amount of silicon fume to cast iron refines the graphite structure, improves the toughness, and prevents white cast iron (hard and brittle structure).

2. Chemical Industry: Core Function: "Synthetic Raw Materials"

Organic Silicone Monomer Synthesis:

99.0% pure, 300-500 mesh silicon powder reacts with methyl chloride (CH₃Cl) in the presence of a copper catalyst to produce methylchlorosilanes (e.g., (CH₃)₂SiCl₂), which are further processed into silicone rubber, silicone oil, and silicone resin (used in sealants, cosmetics, and electronic potting materials).

Silica Preparation:

Silica powder reacts with NaOH or HCl to produce water glass (Na₂SiO₃), which is then acidified and precipitated to produce silica (SiO₂・nH₂O), which is used as a rubber reinforcing agent (to improve tire wear resistance) and a thickener for coatings.

Silane Gas Synthesis: High-purity silicon powder reacts with hydrogen under high temperature and pressure to produce silane (SiH₄), which is used in the chemical vapor deposition (CVD) process for semiconductor chips to form silicon thin films.

3. Other Applications

Refractory Materials:

Industrial-grade silica fume is mixed with Al₂O₃ and MgO to create corundum-silica refractory bricks, used for lining steel blast furnaces and glass kilns. Silica fume improves the erosion resistance and high-temperature resistance of refractory bricks (SiO₂ and Al₂O₃ form mullite, which has a melting point of 1850°C).

Paints and Coatings:

Fine-grained silica fume (500-800 mesh) added to anti-corrosion coatings forms a dense siloxane film, improving the coating's weather resistance and salt spray resistance. It is used in anti-corrosion coatings for marine engineering and bridges.

Metal silicon powder has adjustable size, high purity, reactivity and wide application prospects. It has important applications and development potential in the fields of electronics, steel metallurgy, chemical industry and environmental protection. With the continuous advancement of technology and the increase in application demand, the application prospects of silicon metal powder will be further expanded and expanded.

Q: What's the price difference between industrial-grade and chemical-grade powder?

A: Chemical-grade powder is significantly more expensive than industrial-grade powder, depending on the purity. The price difference between 97% pure powder and 441% pure powder could be one or two thousand yuan per ton. Therefore, before buying, please carefully consider whether your process requires such high purity.

Q: I want to buy 325-mesh powder for organosilicon production. Can you guarantee particle size distribution?

A: Yes. We test each batch of goods with a laser particle size analyzer before shipment to ensure that over 90% of the particles are within your specified mesh size range. For example, if you want 325-mesh, the vast majority of our shipment will be 325-mesh, without many coarse particles or ultrafine powder mixed in. A test report is included with the shipment.

Q: What's the difference between silicon metal powder and ferrosilicon powder?

A: The core difference lies in their composition and applications. silicon metal powder is pure silicon (Si≥97%), while ferrosilicon powder is a Ferro silicon alloy (Si 65%-75%, Fe 20%-30%). Silicon powder has higher purity and is suitable for making organosilicon and high-purity alloys; Fesi powder is cheaper and suitable for steel deoxidation and casting inoculation. Please don't buy the wrong kind.

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