1, zinc alloy advantages and disadvantages:
Advantages: casting zinc alloy fluidity and corrosion resistance is better, suitable for die casting instrument, automobile parts shell.
Disadvantages: zinc alloy die casting the most common defect is surface blistering.
2, aluminum alloy advantages and disadvantages:
Advantages: aluminum alloy density is low, but the strength is relatively high, close to or more than high-quality steel, plasticity is good, can be processed into a variety of profiles, has excellent electrical conductivity, thermal conductivity and corrosion resistance, industry is widely used, the amount of use is second only to steel.
Disadvantages: aluminum alloy in the production process, prone to shrinkage, sand holes, air holes and slag and other casting defects.
Expanded Information:
1, fluidity
Fluidity (fluidity, liquidity) refers to the liquid alloy to fill the casting ability. Liquid alloy fluidity is good, easy to pour the cavity, to obtain a clear contour, size of the casting, on the contrary, the alloy fluidity is bad, it is easy to produce insufficient pouring, cold segregation, porosity and slag and other defects.
In the commonly used alloys, gray cast iron, silicon brass mobility is the best, cast steel mobility is the worst. There are many factors affecting the fluidity, which is mainly the chemical composition of the alloy, pouring temperature and casting filling conditions.
2, shrinkage
Liquid alloy in the cooling process of solidification in the volume and size of the phenomenon known as shrinkage (fraction, shrinkage). Shrinkage is the casting alloy's own physical properties, is the casting of many defects (shrinkage, shrinkage, internal stress, deformation and cracks, etc.) to produce the basic reason. Alloy liquid from pouring into the cavity cooling to room temperature to go through three stages:
(1) liquid contraction (liquidcontraction): from the pouring temperature cooling to the beginning of crystallization of the liquid phase line temperature between the contraction.
(2) solidificationcontraction (solidificationcontraction): from the beginning of the crystallization temperature cooling to the crystallization of the solid phase line temperature of the contraction.
(3) solid state contraction (solidcontraction): from the crystallization temperature cooling to room temperature between.
The liquid shrinkage of alloy and solidification shrinkage is manifested as a reduction in the volume of the alloy, usually expressed in terms of volumetric shrinkage, they are castings produce shrinkage holes, shrinkage defects of the basic reasons. Solid-state shrinkage of alloys is also a volume change, but it only causes changes in the external dimensions of the casting, therefore, it is usually expressed in terms of line shrinkage. Solid-state shrinkage is the root cause of defects such as internal stress, deformation and cracks in castings.
The chemical composition of the alloy, pouring temperature, casting conditions and casting structure are the main factors affecting alloy shrinkage. The actual shrinkage varies depending on the shape, size and process conditions of the casting.
In addition, the alloy liquid in the process of cooling into the casting of the chemical composition of the various parts of the phenomenon of non-uniformity that is, segregation, suction and oxidation have a negative impact on the casting performance.
Baidu Encyclopedia - Zinc Alloy
Baidu Encyclopedia - Aluminum Alloy