Why modify the powder?

Inorganic powders have hydrophilic and polar surfaces, but poor compatibility with organic matrices (plastics, rubber, resins). Direct use can lead to poor performance, so modification is necessary.
(1) Improve dispersibility and prevent agglomeration. Inorganic powders with a large specific surface area are prone to agglomeration, which can lead to defects and a decrease in material strength and poor appearance. The modified powder is uniformly dispersed without clumping.
(2) Improve compatibility with organic matrices. Powder surfaces are hydrophilic (polar), while plastics, rubber, and resins are hydrophobic (non-polar). Direct mixing results in poor interfacial bonding, similar to "sand mixed with butter". After modification, the surface of the powder becomes lipophilic and tightly adheres to the resin.
(3) Enhancing interfacial adhesion and improving mechanical properties, the modified powder forms chemical bonds or strong adsorption with the resin, which can significantly improve tensile strength, impact strength, bending strength, hardness, wear resistance, etc.
(4) Reducing the oil absorption value and improving the processing flowability of unmodified powder can lead to a significant increase in resin viscosity, processing difficulties, and inability to increase the amount of filler added. After modification, the oil absorption value decreases, allowing for high filling and cost reduction.
(5) Improve weather resistance, water resistance, and corrosion resistance to reduce powder water absorption, enhance coating acid and alkali resistance, and improve material aging and yellowing resistance.
(6) Improve electrical and thermal performance, enhance insulation, improve thermal conductivity (such as modifying thermal conductive fillers), and improve flame retardant efficiency (magnesium hydroxide/aluminum).
(7) Improve surface gloss, hand feel, color, commonly used in coatings and plastics to make products more delicate, shiny, and have a better hand feel.

(8) To prevent powder oxidation, self ignition, and reaction, especially for metal powders (aluminum powder, zinc powder), modification can prevent oxidation and self ignition, and improve storage stability.

Which powders need to be modified?

1. Functional powders: titanium dioxide (titanium dioxide), iron oxide red, iron oxide yellow, iron oxide brown, iron black, pearlescent mica, white carbon black, carbon black, nano zinc oxide, hollow glass microspheres, calcium sulfate whiskers, calcium carbonate whiskers, active calcium silicate, flake zinc powder, aluminum tripolyphosphate anti rust pigment, etc;
2. Flame retardant powders: magnesium hydroxide, aluminum hydroxide, etc;
3. Ceramic powders: alumina, zirconia, aluminum nitride, silicon nitride, silicon carbide, barium titanate, strontium titanate, magnesium titanate, zinc titanate, cordierite, magnesium olivine powder, etc;
4. Magnetic powders: neodymium iron boron magnetic powder, strontium ferrite/barium ferrite, iron silicon aluminum, carbonyl iron powder and other soft magnetic powders, nano iron oxide, etc;
5. Carbon materials: graphite, graphene powder, carbon fiber powder, carbon nanotubes, etc;
6. New energy powders: ternary materials, lithium iron phosphate, lithium cobalt oxide, natural/artificial graphite, silicon-based negative electrode, lithium titanate, boehmite, lithium hexafluorophosphate, expandable graphite, zinc borate, silver powder, etc;
7. Metal powders: aluminum powder, zinc powder, copper powder, iron powder, etc;
8. Cosmetics ingredients: silicon dioxide, titanium dioxide, zinc oxide, iron oxide red, iron oxide yellow, iron oxide black, chromium green, ultramarine, manganese violet, hydroxyapatite, etc;
9. Thermal conductive fillers: gold powder, silver powder, copper powder, tin powder, metal nanowires, aluminum oxide, hexagonal boron nitride, silicon carbide, zinc oxide, nanodiamonds, etc.

SAT NANO is a supplier of ceramic powders including alumina, zirconia, aluminum nitride, silicon nitride, and silicon carbide. We can provide surface treatment for these products. Surface modification technology is a key means to improve the performance of ceramic powders. Regarding the five ceramic powders you mentioned, key properties such as strength, toughness, hardness, and hydrolysis resistance of the final ceramic products can be significantly improved through processes such as coupling agent modification and surface coating.
The following is a summary of the specific enhancement data in terms of mechanical and process properties of these five ceramic powders after surface modification:

Ceramic powder	Surface modification methods	solid content	Enhanced data (compared to unmodified samples)
aluminum dioxide	Silane coupling agent A151 modification	-	• Hardness: 85.5 HD • Tensile strength: 52.36 MPa • Impact strength: 10.12 kJ/m ²
	Surface coating of aluminum chloride/aluminum based complex	-	Stamping mechanical strength: increased from a maximum of 35 MPa to 51 MPa (an increase of approximately 45.7%)
zirconia	Polymer dispersant KOS110 modification	46.5%	Vickers hardness: 1814 HV • Shrinkage rate: 21.9%
	Laser microtexture+silane modification	-	Surface water contact angle: from hydrophilic to 159.6 ° (superhydrophobic)
aluminum nitride	Surface esterification reaction of lauric acid (LA)	-	Hydrolysis resistance: The modified powder is placed in water at 40 ℃ for 72 hours, with a stable pH value below 9 and no phase transition occurring
silicon nitride	Low melting point glass powder coating	20%	• Bending strength: increased by up to 14.3% • Fracture toughness: up to 31.1% improvement
	Hydroxylation+silane coupling agent KH560 modification	50%	Bending strength: (407.95 ± 10.50) MPa Fracture toughness: (4.38 ± 0.45) MPa · m ^ {1/2}
silicon carbide	Microwave plasma modification (MPM)		Surface hardness: significantly reduced from 37.04 GPa to 4.71 GPa

Analysis of Modification Effect and Mechanism

In addition to direct data augmentation, different modification methods can also solve specific problems from a mechanistic perspective:

Aluminum oxide (Al2O3) - strength and interface compatibility: By coating the surface with aluminum chloride, the pore structure of the aluminum oxide matrix can be effectively filled, increasing the density and thus increasing the stamping mechanical strength from 35 MPa to 51 MPa. By using silane coupling agents for modification, the interface bonding between nano alumina and resin matrix can be improved, making it a reinforcing phase that significantly enhances the hardness and tensile strength of photosensitive resin.

Zirconia (ZrO2) - High hardness and functionality: By modifying ZrO ₂ powder with polymer dispersants, high solid content and low viscosity 3D printing slurries can be prepared. After sintering, the Vickers hardness of the ceramic can reach 1814 HV, demonstrating excellent mechanical properties. In addition, through laser chemical treatment, micro nano structures can be constructed on its surface and low surface energy substances can be grafted to obtain a superhydrophobic surface with a contact angle of up to 159.6 °, expanding its applications in self-cleaning and other fields.

Aluminum Nitride (AlN) - Hydrolytic Stability: AlN is highly reactive with water, leading to a decrease in performance. Using lauric acid for surface modification, its carboxyl group undergoes esterification reaction with the hydroxyl group on the AlN surface, forming a dense coating layer (with a thickness of about 12.2-16.1 nm). This barrier can effectively prevent the diffusion of water molecules, keeping the pH value of the modified powder below 9 even after being placed in water for 72 hours, greatly improving its storage and processing stability.

Silicon nitride (Si3N ₄) - comprehensive mechanical properties: By coating modification with low melting point glass powder, the glass phase formed during sintering can refine the grain size, and the fracture toughness can be increased by up to 31.1% through toughening mechanism. The modification of silane coupling agent KH560 can improve the compatibility between powder and resin, reduce the viscosity of the slurry, and achieve a solid content of 50 vol%. At the same time, the flexural strength after sintering exceeds 400 MPa.

Silicon carbide (SiC) - improved processing performance: The extremely high hardness of SiC makes it difficult to process. By microwave plasma modification, a relatively soft SiO2 modified layer can be generated on the surface of SiC, causing its surface hardness to drop sharply from 37.04 GPa to 4.71 GPa, thereby changing the material removal method from brittle fracture to plastic removal, greatly improving the efficiency and surface quality of subsequent polishing (roughness Ra can reach 0.31 nm).

From the above data, it can be seen that the surface modified products provided by SAT NANO have a significant increasing effect. If you have any enquiry, please feel free to contact us at admin@satnano.com