Preparation Of Corrosion Inhibitor For Galvanized Equipments In Sulphamic Acid Cleaning

There are tens of thousands of industrial equipments apply to galvanized pipe in ourcountry. Lots of energy will be wasted and can not bring heating and refrigerating into playafter galvanized equipment scaling. By zinc layer binding, equipment structure and the downtime conditions restrictions, many descaling methods all can not be implemented, except themost effective sulphamic acid cleaning. However, sulphamic acid cleaning can remove scale,but seriously corrosion galvanized layer, so effective inhibitor which can not only remove dirtbut also protect equipment safety must be added. Cleaning industry pay close attention toadding corrosion inhibitor to sulphamic acid.The inhibition effects of many compounds were studied by the weight loss method, andthe results indicated that the cinnamic aldehyde and benzaldehyde were better inhibitor forzinc in sulphamic acid. Then thermodynamic property and electrochemical property werestudied. The results showed that the adsorption law of cinnamic aldehyde and benzaldeyde onthe surface of zinc were consistent with the Langmuir adsorption in sulphamic acid. And theadsorption coefficient, enthalpy change, entropy and free energy change, and other relatedthermodynamic parameters were gained. The adsorption process of cinnamic aldehyde andbenzaldeyde were a exothermic process of entropy reducing. Potentiodynamic polarizationcurves investigated that corrosion potential changed small the corrosion current densitydecreased. From30℃to60℃, the inhibition efficency decreased from94.42%to83.63%inthe presence of0.04%cinnamic aldehyde and the inhibition efficency decreased from96.45%to93.79%in the presence of0.2%benzaldeyde. Zinc corrosion reaction activation energyincreased significantly in the amino acid solution,the corrosion process is inhibited.According repeated screening experiments validate prepared two composite inhibitior.he effects of the concentration of JL-1and JL-2, the hydrochloric acid concentration, thetemperature and time on the corrosion rate of aluminum had been studied. The addition of0.7680%JL-1inhibitors: amino acid solution for5%and15%, the corrosion rate of zinc were0.375g m-2h-1and0.75g m-2h-1; between the room temperature to50℃, the corrosion rateof zinc in control of0.5g m-2h-1. When the concentration of JL-2was0.70%inhibition effectbest, acid concentration is not higher than15%, the temperature was below50℃, thecorrosion rate of zinc is lower than that of0.5g m-2h-1. Add the two inhibitors, increasing with time, the corrosion rate of zinc was decreased. The addition of JL-1and JL-2inhibitor,the corrosion potential of zinc are moved, the corrosion current density decreasedsignificantly, two kinds of corrosion inhibitors are cathodic corrosion inhibitor. Add twokinds of corrosion inhibitor galvanized pipe with pale yellow autogenous membrane, nonuniform corrosion phenomena.The above researching conclusions indicate that JL-1has properties of anti-acid,anti-time, anti-temperature, anti-nonuniform and JL-1is efficient environmental protectioncathode type corrosion inhibitor. They have broad application prospect.