国产免费av片无码免费看_无码福利日韩神码福利片_日本成人精品在线免费观看_八戒av无码影视大片_亚洲av美女夜夜_91中文字幕视频_黄色特级毛片在线观看_麻豆自制传媒新剧国产之光_人妻少妇大乳在线放_国产日韩欧美另类重口

Characteristics of inferior aluminium profiles:

1. The cost of aluminium profiles doped with a large amount of miscellaneous aluminium and scrap aluminium has been greatly reduced due to the unqualified chemical composition of aluminium profiles in buildings, which seriously endangers the safety of construction projects.

2. Low-quality aluminium profiles greatly reduce sealing time, chemical reagent loss and cost, but the corrosion resistance of profiles is also greatly reduced.

3. The oxide film is thin. The national standard stipulates that the oxide film thickness of building aluminium profiles should not be less than 10um (micron). Thickness is not enough, the surface of aluminium profile is easy to rust and corrode. Some aluminium profiles without production name, factory site, production license and qualification certificate were sampled and tested. The oxide film thickness was only 2 to 4 um, and some even had no oxide film. Experts estimate that the cost of electricity consumption can be reduced by more than 150 yuan per ton of profiles for each reduction of 1 um oxide film thickness.

4. Unqualified chemical composition. Adding a large amount of miscellaneous aluminium and scrap aluminium can greatly reduce the cost, but it will lead to the unqualified chemical composition of building aluminium profiles and seriously endanger the safety of construction projects.

Unqualified aluminium profiles, when used, will be affected by air, rain, sunshine and other factors, resulting in deformation of aluminium profiles, and even lead to glass cracking, shedding and other phenomena.