Surface mixed and modified powder infiltration technology of magnesium diecast alloy

Abstract

The invention relates to a novel surface modification technology of die cast magnesium alloy. Concentration gradient of surface layer alloy of the magnesium alloy is formed by an infiltration technology; the modified power mixture with different granularity specifications, such as SiC, Al302, Si, Sn, Cr, Al, Zn and Cu and the like, is simultaneously sprayed inside and on the surface of a closed die casting mold cavity evenly; and a surface modified layer is formed in the die casting forming process of the magnesium alloy. The modified layer comprises a sub-surface modified layer and a surface modified layer, and is distributed inwards in a gradient shape along the magnesium alloy surface. The surface modified alloying layer of the invention is continuous and compact, has favorable corrosion resistance and abrasive resistance, and the mechanical property of the casting surface is also improved; the modified alloying layer and the magnesium alloy matrix are metallurgical combination with high combination strength, and surface layer cracking or stripping is not easy to emerge. The modified technology is simple,features easily controlled parameters, environment protection, no pollution, no sticky mold and no injury on a mould, and can be widely used in industrial production.

Description

technical field [0001] The invention relates to a process method for surface modification of a die-casting magnesium alloy. Background technique [0002] Magnesium is the lightest engineering metal material (density 1.8g / cm 3 , which is 2 / 3 of aluminum and 1 / 4 of steel), has a series of unique features such as light specific gravity, high specific strength and specific stiffness, good damping and machinability, good thermal conductivity, strong electromagnetic shielding ability and easy recycling. It can meet the requirements of aviation, aerospace and modern automobile industries for weight reduction and energy saving, and can replace engineering plastics as housings and structural parts of electronic equipment to meet the light, thin, miniaturization, high integration and environmental protection of products and other requirements to improve energy utilization efficiency. However, there are still a large number of technical difficulties to be solved that restrict the fur...

AI Technical Summary

Problems solved by technology

However, there are still a large number of technical difficulties to be solved that restrict the further application of die-casting magnesium alloy parts. This is mainly manifested in the fact that magnesium is a very active metal that is resistant to atmospheric (especially humid air), acidic substances and salts. (especially chloride) has high solubility and fast corrosion rate, and the formed corrosion products are loose and poor in stability. This fatal shortcoming seriously restricts the wide application of magnesium alloys.

[0003] At present, the main methods used for surface modification of magnesium alloys are anodic oxidation, electroplating coating and other processes. Although these processes can slow down the corrosion of magnesium alloys to varying degrees, there are still many deficiencies, such as the relationship between some corrosion-resistant coatings and magnesium alloy substrates. There is an obvious interface between them, the surface tissue is loose and porous, and contains more organic matter, which is easy to crack or peel off, and some process links will also cause pollution to the environment, etc.

In view of the limitations of the existing process methods, all parties are actively committed to the frontier research on the surface modification of magnesium alloys, such as vapor deposition, micro-arc oxidation, ion implantation, laser surface treatment, etc., but the above technologies are still immature. The technology and cost are difficult to be accepted by enterprises, some technologies are still in the exploratory stage, it is difficult to meet the actual requirements, and cannot be widely used in industrial production