聚氨酯保温钢管防腐颜料
Antiseptic Pigment for Polyurethane Thermal Insulation Pipe
品种
Varieties
用于防腐涂料的防锈颜料的品种较多,其罕见有以下几种:
There are many kinds of rust-proof pigments used in anticorrosive coatings, which are rare in the following ways:
①与成膜剂起反响构成致密的防腐涂层;
It reacts with the film forming agent to form a dense anticorrosive coating.
②颜料是碱性物质,溶于水则构成碱性环境;
(2) Pigments are alkaline substances, while soluble in water constitutes an alkaline environment.
③水溶性的成分抵达金属外表使外表钝化;
(3) Water-soluble components reach the surface of the metal to passivate the surface;
④与酸性物质反响使其得到腐蚀才能;
(4) react with acidic substances so that they can be corroded.
⑤水溶性成分或与成膜剂的反响生成物在水中溶解变爲防腐成分等。
_Water-soluble components or reactant products with film-forming agents dissolve into anticorrosive components in water.
机理
Mechanism
防锈颜料的上述防腐作用通常是同时存在的,其防腐机理包括下列物理、化学、电化学的三个方面。
These anticorrosive effects of anti-rust pigments usually exist at the same time. The anticorrosive mechanism of anti-rust pigments includes the following three aspects: physical, chemical and electrochemical.
⑴物理防腐作用。适当配以与油性成膜剂起反响的颜料可以失掉致密的防腐涂层使物理的防腐作用增强。例如含铅类颜料与油料反响构成铅皂使防腐涂层致密,从而增加了水、氧无害物质的浸透。磷酸盐类颜料水解后构成难溶的碱式酸盐,具有梗塞防腐涂层中针孔的效果。而铁的氧化物或具有鳞片状的云母粉、铝粉、玻璃薄片等颜料填料均可以使防腐涂层的浸透性降低,起到物理的防腐作用。
(1) Physical anticorrosion. Proper combination of pigments that react with oily film-forming agents can remove dense anticorrosive coatings and enhance the physical anticorrosive effect. For example, lead-containing pigments and oils react to form lead soap to densify the anticorrosive coating, thus increasing the water and oxygen harmless material immersion. Phosphate pigments hydrolyze to form insoluble alkaline salts, which have the effect of pinholes in anticorrosive coatings for infarction. However, iron oxides or pigments with scaly mica powder, aluminium powder, glass sheet and other fillers can reduce the permeability of the anticorrosive coating and play a physical anticorrosive role.
⑵化学防腐作用。当无害的酸性碱性物质渗入防腐涂层时,能起中和作用变其爲有害物质,这也是无效的防腐办法。尤其是巧妙地采用氧化锌、氢氧化铝、氢氧化钡等两性化合物,可以很容易地完成中和酸性或碱性的无害物质而起防腐作用,或许能与水、酸反响生成碱性物质。这些碱性物质吸附在钢铁外表使其外表坚持碱性,在碱性环境下钢铁不易生锈。
(2) Chemical anticorrosion. When harmless acidic and alkaline substances penetrate into anti-corrosion coatings, they can neutralize and turn them into harmful substances, which is also an ineffective anti-corrosion method. In particular, clever use of zinc oxide, aluminium hydroxide, barium hydroxide and other amphoteric compounds can easily neutralize acidic or alkaline harmless substances and play an anti-corrosion role, perhaps with water, acid reaction to produce alkaline substances. These alkaline substances adsorb on the surface of steel to make it adhere to alkalinity, and steel is not easy to rust in alkaline environment.
⑶电化学防腐作用。从涂层的针孔渗入的水分和氧经过防腐涂层时,与分散在防腐涂层中的防锈颜料反响构成防腐离子。这种含有防腐离子的湿气抵达金属外表,使钢铁外表钝化(使电位上升),避免铁离子的溶出,铬酸盐类颜料就具有这种特性。或许应用电极电位比钢铁低的金属来维护钢铁,例如富锌涂料就是由于锌的电极电位比钢铁低,起到牺牲阳极的作用而使钢铁不易被腐蚀。
(3) electrochemical anticorrosion. When water and oxygen infiltrated through the pinhole of the coating pass through the anticorrosive coating, they react with the anticorrosive pigment dispersed in the anticorrosive coating to form the anticorrosive ion. This moisture containing anticorrosive ions reaches the metal surface, passivating the steel surface (increasing the potential) and avoiding the dissolution of iron ions. Chromate pigments have this characteristic. Perhaps the use of metals with lower electrode potential than iron and steel to maintain iron and steel, such as zinc-rich coatings, is due to the lower electrode potential of zinc than iron and steel, playing the role of sacrificing the anode, so that iron and steel is not easy to be corroded.
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