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Open access

P. Manoj Kumar, G. Gergely, D. K. Horváth and Z. Gácsi

Abstract

The Sn–Ag–Cu (SAC) solders with low Ag or Cu content have been identified as promising candidates to replace the traditional Sn–Pb solder. In this study, an extensive discussion was presented on two major area of mechanical properties and microstructural investigation of SAC305 and SAC405. In this chapter, we study the composition, mechanical properties of SAC solder alloys and microstructure were examined by optical microscope and SEM and mechanical properties such as tensile tests, hardness test and density test of the lead solder alloys were explored. SAC305 and SAC405 alloys with different Ag content and constant Cu content under investigation and compare the value of SAC305 and SAC405. From this investigation, it was reported that tensile strength is increased, with an increase of Ag content and hardness and density were also increases in the same manner.

Open access

D. Koncz-Horváth, G. Gergely and Z. Gácsi

Abstract

In this study, different types of whisker-like formations of Sn-3.0Ag based alloy were presented. In the experimental process the amount of Pb element was changed between 1000 and 2000 ppm, and the furnace atmosphere and cooling rate were also modified. The novelty of this work was that whisker-like formations in macro scale size were experienced after an exothermic reaction. The whiskers of larger sizes than general provided opportunities to investigate the microstructure and the concentration nearby the whiskers. In addition, the whisker-like formations from Sn-Ag based bulk material did not only consist of pure tin but tin and silver phases. The whisker-like growth appeared in several forms including hillock, spire and nodule shaped formations in accordance with parameters. It was observed that the compound phases were clustered in many cases mainly at hillocks.

Open access

G. Gergely, D. Koncz-Horváth, Z. Weltsch and Z. Gácsi

Abstract

This work represents an interesting development in the detection and interpretation of crack evolution in through hole technology (THT) solder joints, which based on the development of general and common method. Serial sectioning is a useful method because it overcomes the problems associated with traditional two-dimensional metallographic techniques by providing information about (micro)structures in three-dimensions.

In our work, serials sectioning with reconstruction method was utilized to visualize the 3D nature of cracks in through hole solder joint. Accurate quantitive analysis of the cracks, such as crack length, position and extension are presented with a help of the developed method: newly defined parameter and serial-cross sectioning method.

Open access

Gergely Horváth and Gábor Csüllög

Abstract

In the past years, many geoparks have been established all over the world, based mainly on the geoheritage, and partly on the cultural heritage, of the regions. Their main aim is to promote the spatial development of certain regions, especially by the development of tourism, including geo- and ecotourism. One of the newest geoparks is the Novohrad-Nógrád Geopark along the border of Slovakia and Hungary, which, having a high status, belongs to the UNESCO Global Geoparks Network. What is remarkable about it is that it was the very first cross-border geopark. Because of historical elements and due to political intentions, borders often play a more disjunctive than connective role, and the changes of the borders in the 20th century often distorted the spatial structure and turned former peripheries into flourishing regions. This was characteristic also of the regions where the Novohrad-Nógrád Geopark was established. Beyond the perspective for the spatial development of these regions, this cross-border geopark forces directly the local authorities and non-governmental organizations (NGOs) on both sides of the border to maintain tighter contacts for co-operation, promoting by this means also better connections between the two countries.

Open access

D. Koncz-Horváth, G. Gergely and Z. Gácsi

Abstract

In lead-free reflow soldering, the presence of voids should be taken into account. For this reason, the effect of the applied heating profiles was examined via the characterization of voids in galvanic and immersion Sn coatings. According to EU Directive 2002/95/EC, the screening of Pb element of reflow soldering (i.e. of electrical and electronic equipment) is necessary; and the practical implementation of this measurement is largely affected by the characteristics of the solder (i.e. the presence of voids and the inhomogeneity of the solder). Comparing the results of the above two coating methods, it was found that by chemical coating more voids were formed and the detected lead content was higher than for galvanic Sn. The standard deviation of Ag and Cu concentrations was mainly influenced by the appearance of large compounds in the second case, while with chemical coating, no large compounds were formed due to the elevated number of voids.

Open access

Zuh S.G, Nagy Ö., Zazgyva Ancuța, Russu O.M., Gergely I. and Pop T.S.

ABSTRACT

Total hip replacement is one of the most frequently performed orthopaedic interventions that can significantly improve the functional status and the quality of life of patients suffering from hip arthrosis. Recently patient satisfaction and patient-reported results of total hip arthroplasty are increasingly emphasised as important tools for the assessments of these interventions. For patients with arthrosis secondary to hip dysplasia, these evaluations can be more difficult, due to younger age and higher functional demands. In this study we compared the Visual Analogue Scale and the Harris Hip Score in order to determine the correlations between these instruments and analyse the possibility of replacing the Harris Score with the Visual Analogue Scale in evaluating the results of hip surgery in patients with dysplastic hips. Our study included 37 women and 4 men (53 hips), with a mean age of 50.96 years (35-58 years), followed for a mean of 4 years postoperatively. Both assessment instruments were used preoperatively and at the follow-up visits. We observed a positive correlation of the values of the Visual Analogue Scale and the Harris Hip Score both preoperatively and postoperatively, with correlation coefficients of +0.71(P <0.001) and +0.77 (P <0.001) respectively. Given these positive correlations, we assumed that the Visual Analogue Scale could replace the Harris Hip Score in the evaluation of patients after total hip replacement. Still it is recommended to combine the Visual Analogue Scale with objective measurements and radiological examination in order to identify significant postoperative changes.

Open access

A. Simon, D. Lipusz, P. Baumli, P. Balint, G. Kaptay, G. Gergely, A. Sfikas, A. Lekatou, A. Karantzalis and Z. Gacsi

Abstract

The scope of the research work is the production and characterization of Al matrix composites reinforced with WC ceramic nanoparticles. The synthesis process was powder metallurgy. The produced composites were examined as far as their microstructure and mechanical properties (resistance to wear, micro/macrohardness). Intermetallic phases (Al12W and Al2Cu) were identified in the microstrucutre. Al4C3 was not detected in the composites. Adding more than 5 wt% WC to the aluminum, microhardness and wear resistance exceed the values of Al alloy. Composites having weak interface bond performed the highest wear rate.

Open access

C. R. Costea, E. Gergely, G. Husi, Laura Coroiu, Helga Silaghi and A. Bara

Abstract

Feedforward and feedback control are new control algorithms used in industrial processes control and very suitable for grinding systems control. The purpose of this paper is to provide a design technique for a control system of a grinding circuit using the feedforward and feedback control. The control scheme is based on the undercompensation of the milling feed flow. The best value of the undercompensation is chosen after analyzing several scenarios. The controller design based on this value proves to provide improved productivity.

Open access

C. R. Costea, Helga Silaghi, Liliana Matica, E. Gergely, G. Husi and Laura Coroiu

Abstract

In this paper, the application of water pumping process is presented. This article presents the design of a human machine interface. Using this interface, it can be possible to track the evolution of pumping water flow. The applications consists of water pumping process simulation. Also, are illustrated and analyzed several cases, depending on the water flow which is inside the tank.