In general,chemical texture etching of aluminum alloys is actually a corrosion process on the surface of aluminum alloys.
From the above corrosion behavior of aluminum,the basic corrosion types of aluminum are:uniform corrosion,pitting corrosion,intergranular corrosion,layered corrosion and corrosion cracking.If there is a potential difference between a certain part of the aluminum alloy and other larger parts,pitting corrosion will occur;if there is a potential difference between the grains and the grain boundary of the aluminum alloy,there is a tendency of intergranular corrosion;if there is stress,this grain Intermittent corrosion will promote corrosion cracking of metals.
Of these corrosion types,controlled pitting and intergranular corrosion are desirable for texture etching,and the rest are sought to be avoided.In order to achieve this goal,the key is how to control different corrosion conditions and corrosion environments,so as to cause different corrosion tendencies and obtain texture effects of different textures and appearances.There are many types of aluminum alloys,many influencing factors,and the relationship is more complicated.For example,different grades of alloy materials have different alloying element compositions,grain composition,alloy composition or distribution uniformity of impurities on the alloy surface.
Even for the same grade of alloy material,there may be different metallographic structures inside due to different batches,different processing methods or other factors.In addition,the surface state of the alloy material before corrosion,the processing and forming method,and the change of the composition content of the corrosion medium during the corrosion process will all affect the formation and texture of the texture.Therefore,it is difficult to develop a chemical texture etching solution that can be widely used in various aluminum alloy materials and can arbitrarily control the texture roughness.
In practical applications,dislocations can only be eliminated by selecting a suitable alloy material and a suitable texture etching solution;or heat treatment of the material(such as those aluminum alloy materials with severe streak corrosion and no uniform texture)Defects,control the appropriate grain size,and then select the appropriate texture etching solution,in order to etch the texture with adjustable roughness and uniform texture.
