Material properties that help solve today's engineering problems.
A alloys deliver the highest tensile strength among the most widely used non-ferrous alloys and match or exceed that of most cast irons.
Yield strength is a major ZA alloy attribute reaching 55,000 psi for ZA-27, that's more than twice that of A380 die cast aluminum, and significantly higher than the strongest plastics. Even ZAMAK 3, the most common alloy has a significant yield strength advantage over A380 aluminum, showing 3 times greater elongation, while maintaining greater hardness and higher stiffness.
Zinc alloys are rigid engineering materials. Their elastic moduli are greater than those of aluminum and magnesium alloys, and are an order of magnitude greater than those of plastic. This, combined with their high strength allows the volume of individual castings to be markedly reduced, saving space and weight.
Toughness and Ductility
High impact strength and good ductility are qualities of zinc alloys that are rarely found in most other casting alloys. Ductility is important for bending and crimpling in post-casting assembly operations, while impact strength provides performance in rough environments. Fracture toughness is also greater than for most aluminum alloys and cast irons.
ZAMAK alloys provide high hardness and abrasion and wear resistance. Optimum hardness is provided by the ZA family whose Brinell Hardness ranges from 95 to 122 when die cast. These values are much higher than the 70 to 85 BHN displayed by aluminum alloys, and much higher than the hardness values of engineered plastics. Along with high hardness, ZA alloys also exhibit excellent abrasion and wear resistance.
As zinc alloys conduct both heat and electricity, they can be used for heat dissipating devices such as heat sinks. Zinc's excellent casting fluidity permits thinner fin and cooling pin design to better dissipate heat. Zinc's excellent electrical conductivity also provides good EMI, RFI and ESD shielding.
Non-sparking and Non-magnetic
Aluminum alloys can generate a spark when struck with a rusty iron component. All zinc alloys, except ZA-27, are classified as "non-sparking" and are the perfect low-cost alternative to bronze in potentially explosive environments.
Zinc's non-magnetic properties are ideal for use in electronics and other applications where delicate moving parts are subject to magnetic disturbances.
This measure of a material's ability to withstand cyclic loading is and important design criterion. Both the ZAMAK and ZA alloys have high fatigue strengths.
Design (Creep) Stress
The allowable design stress, or resistance to creep at room temperature, of ZA alloys is far better than for all but the most esoteric engineering plastics. The room temperature design stress of die cast ZA-27, for example, is 10,000 psi (stress required for the creep of 1% in 100,000 hours). This property allows ZA alloys to be used in applications subject to significant static loading. However, permissible design stress drops with increasing temperature, and a careful review of all constant load applications at temperature is required to determine the suitability of zinc alloys.
Soundness of castings is largely related to product design, tooling layout and process control. Die cast ZAMAK alloys, ZA-8 and ZA-12 are often used for pressure tight applications. For sand and permanent mold casting, ZA-12 is the preferred material. All zinc alloys solidify into a dense strong matrix with excellent pressure tightness.
All of the ZAMAK and ZA alloys have excellent damping capacity. At 20ºC, ZA-27, the highest damping zinc alloy, has nearly ten times greater damping capacity than A380 aluminum or mild steel. At 100ºC damping capacity increases and all of the zinc alloys become "HIDAMETS" (high damping metals) and have damping capacity greater than that of grey cast iron. This property makes zinc alloys the perfect choice for housings where vibration absorption is required.
Zinc has excellent corrosion resistance under normal atmospheric conditions, and in many aqueous, industrial and petroleum environments. Corrosion resistance can be enhanced by such treatments as plating, chromating, painting and zinc anodizing.