Preparation,Characterization And Properties Of Aluminum Triphosphate Composites Powders Ecological Anticorrosive Pigment

Aluminum Triphosphate is a kind of phosphate fine chemicals newly developed which is a kind of non-toxic antirust pigment with excellent performance. As it has good water resistance, strong corrosion resistance, and good performance in enhancing the flame retardant and shock absorption and also good wear-resisting character, so it is widely used in different resin to form anti-corrosion coatings for the use of sheet metal protection. It is currently the antirust pigment with the most promising application prospect. Aluminum Triphosphate is a kind of Louis solid acid with weak acid strength and strong acid degree. Most resin used in the water-soluble paint is carboxylic acid type and it can be dissolved in water only after neutralization with the ammonia, so it is an alkaline polymer. In this case, if acidic pigment is used, to cause agglomeration and even damage. Therefore, Aluminum Triphosphate cannot be used as a pigment directly. There are some shortcomings in the Aluminum triphosphate in production now, including large particle size and distribution range, irregular morphology, high raw material cost non-environmental production process. In addition, as Aluminum triphosphate antirust pigment slightly soluble in water and its hydrolysis resistance is poor, the root ions of aluminum triphosphate dissociate slowly and delay the effect. Although it belongs to long-acting antirust pigment, it can not solve the problem of "flash rust", leading to the fact that it can’t fully replace the traditional toxic lead or chrome antirust pigments. Thus, this thesis mainly focuses on the aluminum triphosphate with its property changed.In order to improve pigment rust resistance, must be modified in order to rust resistance. Three ways of improving the activation of Aluminum Triphosphate antirust pigments can be introduced. First, reducing particle size and adjusting particle shape;Second, chemically modified, adding new Zn2+、Ca2+cation;Third, combining Aluminum Triphosphate with other anticorrosive pigments. Purposefully improves the performance of the system separately antirust pigment, it can form effective protection films fast, The aluminum tripolyphosphate, also reflects the long-acting antirust effect.So that obtain small—sized and evenly scattered modified Aluminum Triphosphate antirust pigments powder, firstly, we can get aluminium dihydric ripolyphosphate as an intermediate product, we use intermediate product with ZnO and Ca(OH)2in upersonic radiation. In my research work, Through changing the conditions of reactive system, such as temperature, reactants’dropping rate, the effect of supersonic radiation, the best crafts parameters were obtained. The compositions and morphologies of media and product were investigated by XRD, SEM, and electrochemistry method. XRD analysis showed that the pattern of powders hadmatched that of AlH2P3O10·2H2O、CaZn2(PO4)2、Zn3(PO4)2、Ca3(PO4)2and unknown compound. And unknown compound peaks appear that this is not just a simple chemical reaction process, but there is a new chemical reaction process, and cause new composite phosphate generated. The finer fraction powders were less aggregation and symmetrically ball-like through SEM analysis, the particle size is Sub-micron.Finally the electrochemical property of the paint film is tested by dynamic potentiostatic polarization curve and the thesis tries to analyze and discuss the anti-rust mechanism of pigment. In the early stage of immersion, current density varies greatly. This kind of phenomenon shows that at the beginning of the impregnation, aluminum tripolyphosphate decompose slowly at first, gradually spread onto the interface of metal-coating. Only in this way, can it react with Fe2+and Fe3+to produce a protective film. Its dissociation and diffusion requires a certain amount of time. With aqueous solution passing through the coating, zinc phosphate and zinc phosphate calcium hydrate gradually and mix with alkyd resin to form a complex phase, thus the gap between the coatings can be reduced to further improve the shielding protection of the coating and the current density levels off. In the end, the current becomes stable; aluminum tripolyphosphate can continuously dissociate P3O105-which can be combined with Fe2+and Fe3+firmly, forming complex and dense MxFey(P04)z to passivate the metal. The application experiment shows that the self-made pigment has a better rust resistance than commercial anti-rust paint. The experimental results show that the modified aluminum tripolyphosphate can be used as excellent ecological antirust pigments in coating industry.