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The aim of the work described was to investigate the effect of the glass microstructure, changed during chemical and thermal treatments, upon the micro-hardness and microcracking of the exchanged specimens. Commercially available soda-lime silicate glass samples have been doped with copper. After ion-exchange, some of the specimens were annealed in the hydrogen atmosphere. Transmission electron microscopy, the XRD and electron diffraction techniques were used to characterize the microstructure of the glass-composites. Additionally, the linear thermal expansion coefficient was measured. The detected strengthening effects have been explained by supposing the formation of copper oxide and some mixed sodium-copper silicates. The induced decrease of the thermal expansion coefficient of this layer results in the formation of strong compressive stresses.

High-ductility cementitious composites (HDCC) have an excellent crack controlled capacity and corrosion resistance capacity, which has a promising application in structure engineering under harsh environment. The purpose of this study is to explore the corrosion mechanism of steel bar in HDCC.

Intact and the pre-cracked HDCC specimens under the coupled action of different dry–wet cycles and chloride attack were designed, and intact normal concrete (NC) was also considered for comparison. Corrosion behavior of a steel bar embedded in HDCC was analyzed by an electrochemical method, a chloride permeability test and X-ray computed tomography.

Steel corrosion probability is related to the chloride permeability of the HDCC cover, and the chloride permeability resistance of HDCC is better than that of NC. Besides, crack is the key factor affecting the corrosion of steel bars, and the HDCC with narrower cracks have a lower corrosion rate. Slight pitting occurs at the crack tips. In addition, the self-healing products and corrosion products fill up the cracks in HDCC, preventing the external aggressive ions from entering and thereby decreasing the steel corrosion rate.

HDCC has a superior corrosion resistance than that of NC, effects of variable crack width on corrosion behavior of steel bar in HDCC under the coupled actions of different dry–wet cycles and chloride attack are investigated, which can provide the guide for the design application of HDCC material in structure engineering exposed to marine environment.

The purpose of this paper was to investigate an influence of a low temperature pressureless sintering process of silver paste on the quality of sintered joints.

The authors analyzed various curing conditions of the paste during its sintering process: 175°C/90 min, 200°C/60 min, 250°C/30 min, 250°C/60 min, 350°C/30 min and 350°C/60 min. They analyzed an influence of the surface plating applied on a ceramic substrate/layer (Cu, Ag, AgPt and Au thick film) on the joints quality. The authors analyzed microstructure and electrical resistance of the joints. They evaluated these properties from the point of view of thermal aging process and changing resistance, after a constant current loading of the sintered joints.

The nanoscale pressureless silver paste can be applied for replacing a pressure-assisted micro-sized silver paste. It was found that the quality of the metal plating applied on the ceramic substrate/layer has a significant impact on the quality of the sintered joints. Copper and AgPt plating have better impact on quality of sintered joints in compare with Ag plating.

This investigation of the quality of the pressureless sintered joints at the silver-silver interface reveals an evident cracking immediately after the silver paste curing. Rapid sintering process typical for silver-based films on the substrate is because of the inter-diffusion between the micro and nanoparticles of silver at interfacial interface.

Besides with a large amount of Na⁺ and Cl⁻ ions in seawater, the presence of Mg⁺² and SO₄⁻² ions builds more complex corrosion mechanism. This paper aims to investigate the corrosion of embedded reinforcement in concrete with the environment of both Cl⁻ and SO₄⁻² anions associated Mg⁺² cation.

The concrete specimens were prepared by using ordinary Portland cement (OPC), and OPC blended with metakaolin (MK) for water to cementitious material ratio (w/cm) 0.48 and 0.51. The concrete mixes were contaminated with the addition of MgCl₂ alone and combined MgCl₂ and MgSO₄ in mix water. Reinforcement corrosion was evaluated by half-cell potential and corrosion current densities (I_corr) at regular intervals. Moreover, the influence of cementitious material type, salt type and w/cm ratio on electrical resistivity of concrete was also investigated. The statistical models were developed for electrical resistivity as a function of calcium to aluminium content ratio, compressive strength, w/cm ratio and age of concrete.

Although the corrosion initiation time increases in the concomitant presence of MgSO₄ and MgCl₂ as internal source compared to MgCl₂, I_corr values are higher in both OPC and MK blended concrete. However, electrical resistivity decreased with addition of MgSO₄. MK blended concrete performed better with increased resistivity, corrosion initiation time and decreased I_corr values.

This study reports statistical distributions for scattered I_corr of rebar in different concrete mixtures. Stepwise regression models were developed for resistivity by considering the interactions among different variables, which would help to estimate the resistivity through basic information.

This paper aims to study the influence of the presence of steel and polyolefin (PO) fibers on the mechanical and durability properties of fiber and hybrid fiber-reinforced concrete (FRC and HFRC).

Hooked-end steel fibers having a length of 35 mm were applied at four different fiber content 1.0%, 1.5%, 2.0% and 2.5%, respectively. PO fibers having the length of 45 mm were also replaced with steel fibers at three different fiber content, 0.6%, 0.8% and 1.0%, to provide HFRC. The compressive, indirect tensile and flexural strengths; electrical resistivity; and water absorption were evaluated in this study.

The results showed that the addition of both steel and PO fibers led to improvements in the mechanical properties of FRC and HFRC. However, the replacement of steel fibers with PO fibers led to a slight loss in mechanical properties. Also, it was concluded that the addition of various types of fibers to concrete decreased both the electrical resistivity and water absorption compared with the control sample. Finally, distance-based approach analysis was used to select the most optimal mix designs.

According to this method, the HFRC specimen including 1.2% of steel and 0.8% of PO fibers was the most optimal mix design among all fiber-reinforced mix designs.

This study aims to investigate the factors responsible for substrate cracking reliability problem in through-glass vias (TGVs), which are critical components for glass-based 2.5 D integration.

Numerical models were used to examine the driving force for substrate cracking in glass interposers due to stress coupling during heating. An analytical solution was used to demonstrate how the energy release rate (ERR) for the glass substrate cracking is affected by the via design and the mismatch in thermal strain. Then, the numerical models were implemented to investigate the design factors effects, such as the pitch distance, via diameter, via pattern, via design, effect from a stress buffer layer and the interposer materials selection on the susceptibility to substrate cracking.

ERR for substrate cracking was found to be directly proportional to the via diameter and the thermal mismatch strain. When a via pattern is implemented for high-density integration, a coupling in the stress fields was identified. This coupling effect was found to depend on the pitch distance, the position of the vias, and the via arrangement, suggesting a via pattern-dependent reliability behavior for glass interposers. Changing the design of the via to an annular shape or a substrate-cored via was found to be a promising approach to reduce the susceptibility to substrate cracking compared to a fully filled solid via. Also, the use of a stress buffer layer, an encouraging design prospect presented for the first time for TGVs in this study, was found to significantly reduce cracking. Finally, alternative via and substrate materials showed lower tendency for substrate cracking, indicating that the reliability of glass interposers can be further enhanced with the implementation of such new materials.

This study signifies the first attempt to comprehensively evaluate the susceptibility to crack formation in glass interposers during heating. Therefore, this study provides new perspectives on how to achieve a significant potential reliability improvement for TGVs.

The purpose of this paper is to provide a modeling perspective relevant to the use of cathodic prevention (CPre) for unconventional concrete in salt‐laden environment.

Based on the experimentally obtained concrete resistivity and chloride diffusion coefficient data, numerical studies with the Nernst‐Planck equations were conducted to investigate the influence of applied voltage (magnitude, direction, and interruption), surface chloride concentration, and concrete mix design on the effectiveness of cathodic prevention and the distribution of ionic species in protected concrete.

The modeling results revealed that the direction of applied electric voltage has significant effect on the distributions of electrical potential and hydroxyl ions in the reinforced concrete, confirming the benefits of cathodic prevention in significantly increasing hydroxyl concentration near rebar and in slowing down the ingress of chloride ingress into concrete. The performance of intermittent CPre was found to be constrained by the variations in concrete resistance from the anode to the cathode. The model was also useful in illustrating the temporal and spatial evolutions on rebar surface in terms of oxygen, hydroxyl and chloride concentrations and electrical potential of top rebar, as well as such evolutions in concrete domain in terms of concrete resistivity and current density for each mix design.

The results reported herein shed light on the fundamental processes defining the performance of CPre for new unconventional concrete in salt‐laden environment.

Aims to evaluate different thick‐film materials for use in strain sensors and temperature sensors on low‐temperature co‐fired ceramic (LTCC) substrates.

LTCC materials are sintered at the low temperatures typically used for thick‐film processing, i.e. around 850°C, The thick‐film resistor materials for use as strain and temperature sensors on LTCC tapes are studied. Thick‐film piezo‐resistors in the form of strain‐gauges are realised with 10 kΩ/sq. 2041 (Du Pont)and 3414‐B (ESL), resistor materials; thick‐film temperature‐dependent resistors were made from PTC 5093 (Du Pont), and NTC‐4993 (EMCA Remex) resistor materials.

The X‐ray spectra of the 2041 and 3414‐Bb low TCR resistors after drying at 150°C and after firing display more or less the same peaks. The electrical characteristics of 2041 resistors fired on alumina and LTCC substrates are similar indicating that the resistors are compatible with the LTCC material. After firing on LTCC substrates the sheet resistivities and TCRs of the 3414‐B resistors increased. Also, there is a significant increase in the GFs from 13 to over 25.

Investigates the compatibility of thick‐film materials and the characteristics of the force and temperature sensors.

This review paper aims to introduce the inkjet printing as a tool for fabrication of flexible/wearable sensors. It summarizes inkjet printing techniques including various modes of operation, commonly used substrates and inks, commercially available inkjet printers and variables affecting the printing process. More focus is on the drop-on-demand printing mode, a strongly considered printing technique for patterning conductive lines on flexible and stretchable substrates. As inkjet-printed patterns are influenced by various variables related to its conductivity, resistivity, durability and dimensions of printed patterns, the main printing parameters (e.g. printing multilayers, inks sintering, surface treatment, cartridge specifications and printing process parameters) are reported. The embedded approaches of adding electronic components (e.g. surface-mounted and optoelectronic devices) to the stretchable circuit are also included.

In this paper, inkjet printing techniques for fabrication of flexible/stretchable circuits will be reviewed. Specifically, the various modes of operation, commonly used substrates and inks and variables affecting the printing process will be presented. Next, examples of inkjet-printed electronic devices will be demonstrated. These devices will be compared to their rigid counterpart in terms of ease of implementation and electrical behavior for wearable sensor applications. Finally, a summary of key findings and future research opportunities will be presented.

In conclusion, it is evident that the technology of inkjet printing is becoming a competitor to traditional lithography fabrication techniques, as it has the advantage of being low cost and less complex. In particular, this technique has demonstrated great capabilities in the area of flexible/stretchable electronics and sensors. Various inkjet printing methods have been presented with emphasis on their principle of operation and their commercial availability. In addition, the components of a general inkjet printing process have been discussed in details. Several factors affect the resulting printed patterns in terms of conductivity, resistivity, durability and geometry.

The paper focuses on flexible/stretchable optoelectronic devices which could be implemented in stretchable circuits. Furthermore, the importance and challenges related to printing highly conductive and highly stretchable lines, as well as reliable electronic devices, and interfacing them with external circuitry for power transmission, data acquisition and signal conditioning have been highlighted and discussed. Although several fabrication techniques have been recently developed to allow patterning conductive lines on a rubber substrate, the fabrication of fully stretchable wearable sensors remains limited which needs future research in this area for the advancement of wearable sensors.

The corrosion of reinforcing steel is considered the most critical problem for the durability of reinforced concrete structures. This study shows the experimental results of the corrosion of steel bars in mortar, using an accelerated test. The results indicate that increasing water/cement ratios accelerate the corrosion of reinforcing steel. In addition, increasing curing times decrease steel corrosion rates. The results also show that the cover to bar diameter ratio plays a significant role in determining the corrosion intensity. For the same cover thickness, the corrosion intensity increases as the steel bar diameter increases.