How to choose matrix adhesive in resin friction materials?
In a variety of friction materials, it can be distinguished by metal base, ceramic base, resin base, carbon/carbon composite class, these friction materials are widely used in trains, aircraft, automobiles, oil RIGS, machinery and other fields, resin based friction materials are widely used in a class of friction composite materials. It is mainly used as brake material and clutch plate for braking or clutch of various running vehicles or machinery.
Friction materials with good performance should be able to meet the following requirements at the same time, mainly:
1, in a certain range to meet the requirements of the friction factor;
2, low wear rate;
3, good thermal decay resistance and thermal recovery;
4, appropriate hardness;
5. Lower noise.
Of course, to choose the brake material that can meet the above properties at the same time, in addition to selecting the appropriate reinforcement material, filler and friction regulator and optimizing the formula, the selection of resin is particularly important. In the friction material industry, the use of ordinary phenolic resin with low heat resistance for decades, such as 2123 #, with the rapid development of the automobile industry, the vehicle running speed has put forward higher requirements for the heat resistance of brake materials, and improving the heat resistance of friction materials has become the focus of research.
In recent years, there have been many modified phenolic resins, such as cashew oil modified phenolic resin, melamine modified phenolic resin, boron modified phenolic resin (FB), etc. These modified phenolic resins have been successfully developed to meet the requirements of many high-performance brake materials.
As for many kinds of phenolic resin that have been produced industrially at present, it is considered that the heat resistance of phenolic resin modified with FB boron is the best after the test and application by scholars at home and abroad. There are many methods to investigate the heat resistance of resin, and we choose thermogravimetric method (TG). According to the TG curve, the decomposition temperature of FB resin can reach more than 500℃, while the phenolic resin will decompose in large quantities when it exceeds 300℃. In friction materials, resin should have a high decomposition temperature and a high weight retention rate (carbon residue rate). The weight retention rate of FB resin at 900℃ is more than 60%.
FB high temperature resistant resin in addition to excellent heat resistance, but also has excellent process performance, the use of no need to add curing agent Hexamethylenetetramine, but also has a variety of rubber such as butadiene rubber, styrene butadiene rubber, EPDM rubber reaction characteristics. According to experts from the National Resin network (www.360gsz.com), high-performance friction materials, in addition to the selection of resin with excellent performance, are also very important in the selection of reinforcement materials. Asbestos fibers widely used in the past are being reduced or discontinued due to environmental problems. Other replacement fibers such as steel fiber, glass fiber, carbon fiber, aramong fiber, sepiolite fiber are used alone or mixed, in the selection to consider the performance, price and other issues, through the combination of different formulations to achieve the required performance.
