The reason why magnetic fluid is so expensive is that it cannot be produced for domestic technical reasons. According to the relevant public information, magnetic fluid is waterproof, oil-proof, acid-resistant and alkali-resistant, which is limited to technical reasons in China and has a high price, so it can only rely on imports. Magnetic fluid, also known as magnetic liquid, ferrofluid or magnetic liquid, is a new type of functional material, which has both the fluidity of liquid and the magnetism of solid magnetic material.