Metal surface pretreatment agent and preparation method and application thereof

Abstract

The invention discloses a metal surface pretreatment agent. Water is used as a solvent, silane is used as a main film forming agent, fluorozirconate and / or fluorozirconic acid are / is used as a second film forming agent, amidogen cage type silsesquioxane (amidogen POSS) is added and used as a film sealant and a repair agent, and acid, a metal promoter, a rare earth compound and a stabilizer can be included as well. In the film forming process of the metal surface coating pretreatment agent, silane film forming and fluorozirconate ceramic film forming are conducted synchronously, mutual doping is conducted, and a dense inorganic-organic hybrid film is formed; and the defects existing in the fluorozirconate film forming process can be repaired in time through silane, the film structure is optimized, multiple kinds of amidogen of the amidogen POSS can react with multiple sites in the film at the same time, the sealing effect can be improved remarkably, and the defects in the film can be well repaired and sealed.

Description

technical field [0001] The invention relates to the field of metal surface treatment, in particular to a metal surface pretreatment agent and its preparation method and application. Background technique [0002] Metal materials are damaged by the action of the surrounding medium, which is called metal corrosion. When metal corrodes, a chemical or electrochemical multiphase reaction occurs between the metal and air, water, etc. on the metal interface, causing the metal to enter an oxidized (ion) state, which will significantly reduce the mechanical properties of the metal material such as strength, plasticity, and toughness. , Destroy the geometric shape of metal components, increase the wear between parts, deteriorate the physical properties such as electrical and optical, and shorten the service life of the equipment. [0003] Application of coating protection on metal surfaces is the most common and important method of preventing metal corrosion. The function of the cove...

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Problems solved by technology

However, in long-term practice, people have found that the organosilanes that can be dissolved in water are mainly aminosilanes and epoxysilanes, but these silanes are not stable after hydrolysis, and generally cross-link within a few hours to a few days

In addition, when the pure silane pretreatment agent is used to treat metals, it first adsorbs on the metal surface through hydrogen bonds. Since the dehydration between Si-OH and Me-OH and Si-OH and Si-OH requires certain conditions, at room temperature or 50 ° C It is difficult to quickly form a stable three-dimensional network structure under the following conditions. Therefore, compared with chromic acid passivation and phosphating, the pure silane treatment agent has a slower film formation speed, and often requires a heating and curing process to obtain a stable silane film. The film cannot be washed with water before the film is completely formed, so it cannot directly replace the phosphating process on the existing phosphating production line

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