The Research And Evaluation Of The Corrosion Inhibitors For The Aluminum Equipment In Hydrochloric Acid Cleaning

Possessing low price, high conductivity of heat and good scalability, aluminum finds wideapplication in industry. But, in aluminum equipment use process, as a result of the formationof scale, the heat transfer efficiency decreased and even lead to early retirement. Hydrochloricacid cleaning can effectively remove scale，but the corrosion of aluminum is very serious. Touse correctly corrosion inhibitor is to the effective method of preventing metal and its alloyfrom corroding in the corrosive condition. So it’s important to develop new type corrosioninhibitors for aluminum used in hydrochloric acid.The inhibition effects of hundreds of single-component organic and inorganic corrosioninhibitors were studied by the weight loss method, and the results indicated that thebenzalkonium bromide and cinnamic aldehyde were better inhibitor for aluminum in3%hydrochloric acid. The influence of temperature on the corrosion performance ofbenzalkonium bromide and cinnamon aldehyde were analyzed by thermodynamic study. Theresults showed that the adsorption law of benzalkonium bromide and cinnamic aldehyde onthe surface of aluminum were consistent with the Langmuir adsorption in3%hydrochloricacid medium. And the adsorption coefficient, enthalpy change, entropy and free energychange, and other related thermodynamic parameters were gained. The adsorption process ofbenzalkonium bromide and cinnamic aldehyde were a process of entropy and exothermicreducing, free energy increasing with temperature, corrosion rate decreasing. Potentiodynamicpolarization curves investigated that the corrosion current density decreased. Benzalkoniumbromide and cinnamon aldehyde acted as mixing type inhibitors because the cathodic andanodic process of aluminum had great change and the change of corrosion potential wassmall.The benzalkonium bromide and cinnamic aldehyde were mixed with variety ofcompounds showed better inhibition effect by orthogonal experiment. JT-1and JT-2corrosion inhibitor for aluminum were synthesized which showed high corrosion inhibitingperformance in the hydrochloric acid medium. The effects of the concentration of JT-1andJT-2, the hydrochloric acid concentration, the temperature and time on the corrosion rate ofaluminum had been studied. The results showed that the corrosion rate of aluminum wasreduced and the inhibition efficiency of JT-1and JT-2were increased with increasing theinhibitor concentration in3%hydrochloric acid medium. When the concentration of JT-1and JT-2inhibitor were increased to1%, the maximum inhibition efficiency was97.5%and97.8%, respectively. When the concentration of hydrochloric acid reaches to10%with1%JT-1and JT-2inhibitors, the maximum inhibition efficiency reached up to90.3%and90.5%.It was indicated that JT-1and JT-2showed excellent corrosion inhibition performance.Though the corrosion rate of aluminum was increased with increasing temperature, theinhibition efficiency of aluminum was still up to92.4%and92.6%when the temperaturereached to60℃, indicating that the of JT-1and JT-2inhibitors had good performance resistto high temperature. JT-1and JT-2inhibitors had lasting inhibition performance for thecorrosion rate of aluminum within24hours. Potentiodynamic polarization curves investigatedthat the corrosion current density decreased. JT-1and JT-2inhibitors acted as cathodeinhibitors because the corrosion potential moved to positive direction.In summary, JT-1-and JT-2inhibitors had better inhibition performance for aluminum inhydrochloric acid and strong anti-interference, which had a very broad application prospectand development value.