Materiais de liga de zinco: Composição, processos e utilizações

Zinc-based alloys are mainly zinc, adding aluminum, copper, magnesium and other elements, with a low melting point, easy processing, lightweight, corrosion-resistant, platable and other characteristics, widely used in automotive, electronics, industrial hardware and aerospace fields, Zamak / ZA system to meet the diversified needs of the selection of performance, process and corrosion resistance requirements should be taken into account.

Composition and Classification of Zinc Alloys

Core Elements and Role

Elemento	Gama de conteúdos comuns	Papel principal
Alumínio (Al)	3%-27%	Melhorar a força, a dureza e a resistência ao calor, melhorar a fluidez.
Cobre (Cu)	0.5%-3%	Aumenta a força e a resistência ao desgaste, mas o cobre elevado reduz a ductilidade.
Magnésio (Mg)	0.02%-0.06%	Reforço de traços, refinamento de grãos, melhoria do desempenho global
Níquel (Ni)	0.06%-0.10%	Maior resistência à corrosão e estabilidade a altas temperaturas (principalmente em Zamak 7)
Estanho (Sn), ferro (Fe), manganês (Mn)	Traço	Ajuste da capacidade de fundição para controlar a influência das impurezas

Typical Zinc Alloy Series Comparison

Series	Representative Grade	Principal Composition (%)	Characteristics
Zamak	Zamak 3	Zn-4Al-<0.05Mg	Best overall performance, most commonly used
	Zamak 5	Zn-4Al-1Cu-<0.05Mg	Higher strength and hardness than Zamak 3
	Zamak 2	Zn-4Al-3Cu-<0.05Mg	Higher strength and wear resistance, but lower ductility.
	Zamak 7	Zn-4Al-0.06Ni-<0.03Mg	Higher purity and better corrosion resistance.
ZA series	ZA-8	Zn-8Al-small amount of Cu, Mg	High strength die casting, good toughness
	ZA-12	Zn-12Al-small amount of Cu, Mg	Suitable for heavy-duty castings, improved mechanical properties.
	ZA-27	Zn-27Al-small amount of Cu, Mg	Extremely high strength, but slightly poor machinability

International standard naming system for zinc alloys

Country/Region	Standard No.	Naming Example	Naming Description
U.S.A.	ASTM B86, B240	ZP3, ZP5	Numbered according to major components and properties.
Europe	EN 1774, EN 12844	ZL0430	Z = zinc, L = die casting, 04 = aluminum content of 4%, 30 = copper content of 3.0%.
China	GB 8738-88	ZnAl4Cu1	Identification by element and content
Japan	JIS H2201, H5301	ZDC2, ZDC3	Zamak-like classification system

Physical and Chemical Properties of Zinc Alloys

Propriedades mecânicas

• Tensile strength: 200-440 MPa (higher than most plastics)
• Hardness: 80-120 HB (can be upgraded by heat treatment)
• Elongation: 10-25% (suitable for complex molding)

Thermal Properties

• Melting point: 380-420°C (50% lower than aluminum)
• Coefficient of thermal expansion: 27.4 x 10⁻⁶/°C (design clearance to be considered)
• Thermal conductivity: 110 W/m-K (better than stainless steel)

Electrical and Magnetic Properties

• Electrical conductivity: 28% IACS (28% of pure copper)
• Magnetic conductivity: non-magnetic (suitable for electronic equipment)

Zinc Alloy Processing Technology

Die Casting Technology

• Temperature control: 410-430°C for molten zinc liquid
• Pressure parameters: 400-1000 bar (adjusted according to part complexity)
• Mold design: draw slope ≥ 1°, wall thickness 1.5-5 mm

Extrusion and Rolling

• Applicable alloys: ZA27 (high aluminum content)
• Processing limitations: deformation rate ≤80% to avoid cracking

Machining

• Cutting speed: 60-150 m/min recommended
• Tool selection: carbide or diamond coated

Surface Treatment and Anti-Corrosion Program

Comparison of Commonly Used Processes

Process	Cost	Salt Spray Resistance Time	Applicable Scenarios
Chrome plating	High	500 hours	High-end bathroom hardware
Nickel plating	Medium	300 hours	Electronic connectors
Phosphating	Low	100 hours	Internal structural parts

Anti-Corrosion Strategy

• Marine environment: choose ZN series + nickel plating treatment
• Acidic medium: use ZT series + epoxy coating
• High temperature environment: give priority to anodizing treatment

Design and Selection Guide

Structural Design Principles

• Uniform wall thickness: avoid shrinkage (recommended 2-4 mm)
• Rounded corner design: R≥0.5 mm to reduce stress concentration

Balance Between Cost and Performance

• Low load parts: Zamak 3 (15% cost reduction)
• High wear demand: choose ZC1 (1% copper content)

Reliability Test Standards

• Salt Spray Test: ASTM B117 (≥96 hours)
• Impact test: ISO 148 (≥20 J at room temperature)

Typical Applications of Zinc Alloy

Automotive Industry

• Engine mounts
• Sensor housings

Electrical and Electronics

• 5G base station heat sink
• USB Port Housing

Building Decoration

• Door and window hinges
• Outdoor Sculpture

Consumer Products

• Eyeglass frames
• Puxadores para móveis

Enclosure Fittings

• Handles
• Dobradiças
• Trincos

FAQ

Q:What are the key indicators for material selection?

A:Prioritize the mechanical properties, taking into account the mobility and cost control.

Q:What are the mechanical parameters?

A:Zamak 3 basic type vs ZA series high strength alloy performance comparison

Q:What are the key points for safe operation?

A:Finished products are non-toxic, processing requires dust protection and standardized protection.

Conclusão

Zinc-based alloys have low melting point, easy processing, corrosion resistance and good mechanical properties, suitable for automotive electronics and other fields, Zamak/ZA series covers a wide range of needs, the selection of performance, process and corrosion requirements should be integrated.