Friedel’s Salt and Hydrotalcite – Layered Double Hydroxides and the Protection against Chloride Induced Corrosion

This paper discusses some aspects of corrosion protection that fly ash and GGBFS offer to steel reinforcement in concrete. It focuses on the formation of two types of Layered Double Hydroxides (LDH’s). These are Friedel’s salt and Hydrotalcite. While Friedel’s salt is known to form in fly ash blends, the authors support the evidence of hydrotalcite formation in GGBFS blends as a result of the magnesium content in the slag. The paper discusses the corrosion protection performance of GGBFS concrete and compares it to that of fly ash concrete. The paper shows the superior advantage of including GGBFS for corrosion protection. The authors explored the probable reasons for this significant advantage and relate it to the formation of hydrotalcite in GGBFS concretes

Application of acoustic emission sensor to investigate the frequency of tool wear and plastic deformation in tool condition monitoring

The metal cutting process initiates with the occurrence of plastic deformation of workmaterial and is followed by tear and removal of material from the workpiece. This process ultimately damages cutting tool and causes tool wear. An acoustic emission (AE) sensor has been employed to measure the signal frequency in machining. The AE signal component of tool wear and plastic deformation in turning are separated by simulating the process of tool wear by a grinding test where the workpiece of grinding test is the same tool-insert for tuning test, and the process of tool wear in turning is replicated by the process of material removal in grinding. The frequency of tool wear for this particular investigation is found to lie between 67 kHz and 471 kHz whereas for plastic deformation of workmaterial, it has a fluctuation within the range starting from 51 kHz to some value within 471 kHz