Throwing Power of Embedded Anodes for the Galvanic Cathodic Protection of Steel in Concrete

The chloride-induced corrosion of steel reinforcement is one of the main causes of deterioration of reinforced concrete structures. Cathodic protection (CP) of steel in concrete is a widely accepted repair technique to reduce, or completely stop, reinforcement corrosion. One possible method of cathodic protection is through the use of embedded galvanic (sacrificial) anodes, consisting of a zinc metal core surrounded by a precast alkali-activated cementitious mortar. The design of a CP system based on embedded galvanic anodes is based on the required amount of zinc material and the throwing power of the anode (i.e., radius around the anode in which the steel achieves sufficient protection). In this research, the protection of steel reinforcement in concrete surrounding an embedded galvanic anode was evaluated through depolarisation measurements with internal and external reference electrodes. Based on these measurements, the throwing power of the galvanic anode was determined, taking into account the 100 mV depolarisation criterium (cf. EN ISO 12696:2016). Additionally, the influence of the degree of chloride contamination of the concrete and relative humidity and temperature of the environment on the throwing power was evaluated. The results show a strong influence of chloride contamination on the throwing power of the galvanic anodes, in the sense that a higher chloride concentration in the concrete matrix leads to a reduction in the throwing power. This reduction can be related to the more negative potential of corroding steel reinforcement compared to passive steel, thus leading to a lower driving potential for the galvanic reaction. Especially when the chloride concentration is higher than 1 m% vs. cement mass, the throwing power is greatly reduced. Additionally, it was found that a higher relative humidity (RH) of the environment (and consequently, a higher RH of the concrete) resulted in a higher throwing power.

THE THROWING VELOCITY AT DIFFERENT PHASES OF TEACHING HANDBALL ELEMENTS

The aim of this research is to study the ball throwing velocity at different phases of teaching handball elements to female students in their first year of study at Faculty of Kinesiology, Zagreb. The set of variables contains three throwing velocity tests: 1. handball throwing velocity from the standing position (ST), 2. basic shot throwing velocity (RT) and 3. jump shot throwing velocity (JT). The speed of the ball was estimated by a radar gun (Stalker ATS) three times for each shooting type and it was expressed in km/h unit. Measuring was conducted twice in the course of the summer semester of the academic year 2017/2018. The first measuring was carried out after the first lesson and the second one a month later. The average throwing velocities recorded during the first measuring were: ST - 59.25 km/h, RT - 61.60 km/h and JT 61.62 km/h. On the following occasion, the average results were: 59.36 km/h (ST), 61.33 km/h (RT) and 61.33 km/h (JT). No statistically significant differences in the observed set of variables were found by using the t-test for the dependent samples on either occasion. The obtained results can be interpreted in regard to the methods of directing and evaluating the teaching process, as well as in regard to an effective program for improving explosive throwing power.

Effects of Chemical Compositions on Plating Characteristics of Alkaline Non-Cyanide Electrogalvanized Coatings

The effects of zinc and sodium hydroxide concentrations in an alkaline non-cyanide zinc bath on the electrodeposition characteristics of zinc deposits are systematically investigated. Using microstructural and phase analyses of specimens with specifically designed geometries, the study indicates that the bath formulations critically control the electrogalvanizing characteristics and affect the coating surface morphology, deposition rate, throwing power, coating uniformity, and residual stresses developed during and after electrogalvanizing. The coatings produced from baths with a moderate Zn-to-NaOH ratio of 0.067–0.092 appear to provide uniform and compact deposits, moderately high deposition rate, and relatively low residual stresses.

Periodic Pulse Plating of Mid-Aspect Ratio Printed Circuit Boards for Enhanced Productivity

ABSTRACT Pulse plating of copper has typically found use in the plating of very difficult, high aspect ratio printed circuit boards. Its ability to provide throwing power deep within through holes with aspect ratios as high as 30:1 is well established. This technology has long been thought of as a high technology, high cost, specialty process applicable only to high end products. This paper will discuss the advantages that pulse plating offers over conventional DC copper plating in high volume production applications for panels with aspect ratios of up to 12:1. These advantages are reduced plating time, increased throughput, and reduced plated copper thickness on the panel surface while meeting minimum in-hole copper thickness requirements.