Modern building doors and windows can be roughly divided into plastic windows, composite materials windows and aluminum alloy windows according to the types of profiles. Among them, aluminum alloy windows are the main building doors and windows products in our country today, accounting for a considerable proportion in today's buildings. In fact, the air tightness and water tightness of aluminum windows are superior. This is because, compared with plastic windows with the same section, the moment of inertia of aluminum alloy windows is 3-4 times that of plastic windows; with the use of thermal insulation bridges in aluminum alloy profiles, the thermal insulation and thermal insulation properties of aluminum alloy windows are greatly improved, which is very suitable for the energy-saving requirements vigorously advocated today.
It plays an important role in the quality of aluminum doors and windows. Due to the continuous development of modern technology, more and more door and window hardware accessories (handle, handrail, hinge, slide rail, connectors, etc.) are also pouring into the market. The shapes and colors of these products are various, which make the practicability and appearance of doors and windows more colorful. However, due to the different materials of parts and surface decoration layer, their service life (mainly refers to the corrosion resistance, durability and strength) is very different. Even if the aluminum alloy window accessories with the same color and feel are similar, the gap can reach several times or even dozens of times. Aluminum alloy door and window hardware must have enough mechanical strength, but also pay attention to whether the selected material can maintain good corrosion resistance when contacting with aluminum alloy. Whether the hardware of aluminum alloy doors and windows can meet the design life requirements is very important for the safety and durability of aluminum alloy doors and windows in the use process. Only when the two are combined well can the characteristics of beautiful and durable aluminum alloy doors and windows be brought into play.
Corrosion characteristics and mechanism of aluminum alloy door and window hardware
1. Accessories materials
The structure and material of different window hardware fittings are not the same, and the general aluminum alloy door and window hardware accessories material is matched with the profile. Manufacturers first choose profiles, and then choose hardware accessories. This will sometimes lead to type selection is not standard, can not find matching hardware. Now most manufacturers will first consider the profile and hardware accessories, and then give the choice. Material is the key material basis to ensure the performance, quality and safety of doors and windows. At present, most of the materials used in aluminum alloy doors and windows, including various accessories, have national or industrial standards, but some materials are produced without national or industrial standards. Generally speaking, in the materials of aluminum alloy door and window accessories, die-casting zinc alloy is used for handle and transmission parts; aluminum alloy is used for hinge, etc.; stainless steel is used for hinge shaft and lock point; zinc alloy or stainless steel material is used for lock seat; stainless steel is used for sliding brace and wind brace; nylon 66 modified plastic is used for plastic parts. For the metal parts, according to the different environments used, the effective surface treatment is carried out, mainly considering the atmospheric corrosion resistance, the corrosion with the materials contacted and the electrochemical corrosion between different metal materials.
2. Corrosion characteristics
Aluminum and aluminum alloy is a kind of metal material with high conductivity and heat conduction. Its surface is easy to be passivated in natural state. The surface is oxidized to form a1203.3h20 under wet and acidic conditions. Hydrated alumina itself is relatively stable. Moreover, the door and window profiles made of aluminum and aluminum alloy are generally subject to specific treatment and have high performance of anti-corrosion. The weak parts of anti-corrosion are mainly on hardware The galvanic corrosion of hardware is not only in itself, but also affected by the electrode of aluminum profile. Under certain conditions, the corrosion will be carried out continuously.