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As an indispensable functional material in modern industry, the performance optimization of bronze powder has always been a key focus in the field. Among various metallic pigments, bronze powder holds a prominent position in decorative coatings and functional materials due to its unique metallic luster and vibrant color expression.
However, traditional bronze powders face technical bottlenecks such as susceptibility to oxidation and poor weather resistance, which have long limited their application in high-performance scenarios. In recent years, breakthroughs in surface modification technologies—passivation treatment and silica coating—have successfully addressed these challenges, propelling bronze powder applications into a new era of development.
I. Passivated bronze powder: Revolutionizing Aqueous Systems
1. Technological Innovation Principles
Passivation treatment constructs a nanoscale passivation film on the surface of bronze powder using chemical passivators. This process employs an organic-inorganic composite passivation system, forming a dense passivation layer through chelation reactions. Organosilane coupling agents chemically bond with the metal substrate, while inorganic phosphate compounds create a three-dimensional network via hydrolysis and condensation. This dual protection mechanism significantly enhances chemical stability.
2. Performance Breakthroughs
Passivated bronze powder exhibits revolutionary improvements:
– Anti-oxidation capability improved by over 300%, maintaining color stability for over 200 hours at 85°C.
– Nanoscale dispersion in aqueous systems, with Zeta potential absolute values exceeding 40mV, ensuring storage stability for over 12 months.
– In waterborne acrylic systems, hydrolysis resistance increases by 5×, fully complying with the EU EN71-3 heavy metal migration standard.
3. Application Expansion
The technology overcomes limitations in water-based inks:
– In food packaging printing, VOC emissions are reduced by 90% while achieving solvent-level metallic effects.
– For low-temperature curing systems (80–120°C), IMD molding processes compatible with PET substrates deliver 5B-rated adhesion for metallic decorative layers.
– Eco-friendly masterbatches are now used in sensitive fields like children’s toys and medical devices.
II. Silica-Coated bronze powder: Guardian of High-Temperature Processing
1. Core Technological Breakthroughs
Chemical vapor deposition (CVD) coating technology enables precise control of silica nanolayers. Under 600–800°C reaction conditions, silicon source gases grow 20–50nm dense amorphous SiO₂ layers on copper powder surfaces. The gradient-structured coating features an inner chemically bonded layer and an outer physical barrier layer, with thermal expansion coefficients matching the substrate to ensure structural integrity at high temperatures.
2. Performance Advantages
Testing reveals exceptional properties:
– After 2 hours at 300°C, color difference ΔE < 1.5, far surpassing industry standards.
– Salt spray resistance exceeds 1,000 hours, with HCl gas tolerance reaching 500ppm.
– In PC/ABS alloy injection molding, the powder withstands 280°C mold temperatures for 2 hours, achieving 98% dispersion uniformity.
3. Industrial Applications
– Automotive components: High-temperature resistant identification coatings in engine compartments.
– Powder coatings: Metallic finishes endure 220°C/30min curing processes.
– 5G thermal management: Dual functionality in electromagnetic shielding and heat resistance for communication device housings.
III. Comparative Analysis and Synergistic Development
1. Process Characteristics
– Passivation focuses on chemical stability, operating at 50–80°C, ideal for heat-sensitive systems.
– Silica coating emphasizes physical barriers, requiring high-temperature reactions but delivering longer-lasting protection.
– Complementary weather resistance: Passivated products excel in humid environments, while silica-coated variants dominate in dry, high-heat conditions.
2. Synergistic Applications
Emerging hybrid technologies combine both advantages. For example, in automotive wheel coatings:
– Initial passivation enhances early-stage corrosion resistance.
– Subsequent silica coating boosts long-term weather resistance, passing 240h salt spray and 2,000h xenon aging tests.
3. Market Value Insights
– Global modified bronze powder market grows at 12% annually, with aqueous systems (35%) and high-temperature applications (28%) leading.
– In new energy vehicles, silica-coated powders for battery casing decoration show 200% year-on-year growth.
Conclusion
From lab breakthroughs to industrial adoption, surface modification technologies for bronze powder exemplify the material engineering philosophy: “Small changes make big differences.” The synergy between passivation and silica coating redefines the performance boundaries of metallic pigments, driving the surface treatment industry toward high performance and sustainability. Under the dual engines of smart manufacturing and green chemistry, functional metallic pigments are ushering in a new industrial chapter.
