The winding layer has turned white
Thread Content
After the winding and curing process for the gas cylinders in my company was completed, hydraulic pressure was applied; after that, the entire surface of the gas cylinders turned white. What could be the reason for this? Could any teacher please analyze this? The specific details are as follows: Wrapping layers: carbon fiber, glass fiber, resin, curing agent (organic anhydrides). Water pressure: rust inhibitor concentration of 5%, pH 8-11
The whitening of the gas cylinder surface may be caused by chemical reactions that occur during the water pressure process. This situation may be related to the components in the resin curing agent and the rust inhibitor in the winding layer. 1. Resin curing agents (organic anhydrides): They may react with hydrogen ions (H+) in water during the hydrostatic pressure process, producing acidic substances. These acidic substances react with the coating on the surface of the gas cylinder, causing whitening. 2. Rust inhibitors: The components in rust inhibitors may react with the material on the surface of the gas cylinders, producing certain chemical substances. These chemicals may interact with the acidic substances formed during the hydrostatic pressure process, leading to whitening. It is recommended to try the following methods to solve the problem: 1. Adjust the pH range during the adjustment of water pressure, in order to prevent excessively high or low pH levels from having an adverse effect on the coating layer and the rust inhibitor. 2. Perform appropriate winding layer treatments prior to applying water pressure, such as cleaning and grinding, to improve the surface quality of the winding layer. 3. Try using different resin curing agents or rust inhibitors, and choose components with better compatibility. To diagnose the issue more accurately, it is recommended that you consult a professional teacher or expert in materials science or chemistry for a detailed analysis. .
The water used for the pressure test should come into contact with the inner surface of the container, but what is turning white is the outer surface of the container. So do you think what was said on the second floor makes sense? The whitening of your outer surface is likely caused by the slight deformation of the container due to the hydrostatic test.
It is caused by stress-induced deformation and can be attributed to the result of mechanical aging. If there is no other data to support it, a rupture test should be conducted for evaluation. .
This phenomenon can also occur in the air respirator cylinders, such as slight delamination of the fibers due to stretching forces. I’m quite averse to ChatGPT’s formatted, off-topic responses.
If this container is subjected to external pressure, then what I said isn’t correct. In the past, when I tested FRP pipes made of API15H, I carried out internal pressure tests, with pressures approaching 10 MPa; such issues did not occur on the outer surface of the pipes. At most, the pipes would change color when placed outdoors, due to ultraviolet radiation – and even with UV-resistant additives added, they still change color. Clear water does not cause whitening; it is rather due to the reaction between the rust inhibitor and the unfully cured surface resin.
The whitening might be caused by tiny bubbles; you can try adjusting the resin formula