Thermal analysis and microscopic characterization of the piston alloy AlSi13Cu4Ni2Mg

In this research paper, the phases identified by thermal and microscopic analysis of the piston alloy AlSi13Cu4Ni2Mg, which was solidified under different conditions, are presented and compared with different piston alloys. Piston alloys are a group of casting Al–Si alloys, well-known as wear resistant materials, which are widely used as the piston materials for internal combustion engines because of their low thermal expansion coefficient and high wear resistance when alloyed with other elements such as copper, magnesium and nickel. Depending on the combination of alloying elements and other impacting factors, pistons alloys with different mechanical and physical properties are obtained.     

Dicing of hard and brittle materials with on-machine laser-dressed metal-bonded diamond blades

The ultra-precision dicing of hard and brittle materials causes high wear on the abrasive tool which results in the deterioration of blade cross section as well as the decrease of diamond grain exposure. Resin-bonded diamond blades are used due to their in-process self-sharpening capability. Nevertheless, the shape of the blade cross section generated by self-sharpening is random which leads to poor accuracy when precise grooves need to be produced. Metal-bonded diamond blades feature higher tool lifetime and shape accuracy compared to resin-bonded blades, but are not capable of performing self-sharpening. In this study, the laser dressing of metal-bonded diamond blades is investigated to enable their use in the ultra-precision dicing of hard and brittle materials by continuous laser dressing. We investigated laser dressing with and without the presence of cooling water. The sharpness (grain exposure) after dressing is measured by the cutting face surface roughness. The dicing performance is evaluated by observing the dicing results in terms of cutting depth consistency and by monitoring the spindle power during dicing. Dicing blades which have been laser dressed in an environment with coolant feature less grain exposure than dicing blades which have been laser dressed in dry condition. The dicing results show an improvement in the sharpness and durability of laser-dressed dicing blades in comparison with new or conventionally dressed blades. The ability to apply and perform laser dressing on a dicing machine in an environment with coolant shows the feasibility of laser technology for continuous dressing.     

A continuous process for the ultrasonic spray pyrolysis synthesis of RuO2/TiO2 particles and their application as a coating of activated titanium anode

Synthesis and subsequent deposition of sub-micron spherical RuO₂/TiO₂ particles onto titanium were performed by continuous process in two connected reactors, exclusively applied for this purpose. Synthesis of particles was achieved by ultrasonic spray pyrolysis method in the first reactor. The deposition of thus produced RuO₂/TiO₂ onto an expanded titanium substrate was performed at 500 °C afterwards in the second, specially constructed, reactor equipped by high-voltage electrostatic field. Basic electrochemical properties of the obtained RuO₂/TiO₂ particles were checked in a form of the coating on Ti deposited from the suspension of the material produced in the first reactor. Thus prepared anode was investigated by cyclic voltammetry (CV), polarization measurements in O₂ (OER) and Cl₂ (CER) evolution and the accelerated stability test in diluted chloride solution. The morphology and composition of the deposited RuO₂/TiO₂ were checked by scanning electron microscopy/energy dispersive X-ray spectroscopy analysis. Analysis of the results obtained for OER and CER showed that Tafel slopes for these reactions were in accordance with the values for this kind of material. The CV response was of usual characteristics too. The accelerated stability test revealed acceptable anode stability.     

Use of ionic liquid in leaching process of brass wastes for copper and zinc recovery

Brass ash from the industrial brass manufacturer in Turkey was leached using the solutions of ionic liquid （IL） 1-butyl-3-methyl-imi-dazolium hydrogen sulfate （[bmim]HSO4） at ambient pressure in the presence of hydrogen peroxide （H2O2） and potassium peroxymonosulfate （oxone） as the oxidants. Parameters affecting leaching efficiency, such as dissolution time, IL concentration, and oxidizing agent addition, were investigated. The results show that [bmim]HSO4 is an efficient IL for the brass ash leaching, providing the dissolution efficiencies of 99%for Zn and 24.82%for Cu at a concentration of 50vol%[bmim]HSO4 in the aqueous solution without any oxidant. However, more than 99%of zinc and 82%of copper are leached by the addition of 50vol%H2O2 to the [bmim]HSO4 solution. Nevertheless, the oxone does not show the promising oxidant behavior in leaching using [bmim]HSO4.     

Numerical modelling of ceramic mems structures with piezoceramic thick films

The correctness of the material parameters that are used in numerical models is of key importance for any numerical analysis. Because of a lack of available material parameters and standard procedures for characterising piezoceramic thick films, special attention has to be paid to providing data for accurate material models. In the presented work, thick-film (TF) lead–zirconate–titanate (PZT) structures made on different ceramic substrates were considered. In order to obtain proper material parameters for TF PZT some unconventional characterisation approaches were used e.g. nano-indentation test for evaluation of the compliance of the piezo film. The results of characterising TF PZT structures on two different ceramic substrates, Al₂O₃ and pre-fired low temperature cofired ceramic (LTCC), are presented. For validation purposes simple cantilever-type actuators were modelled using the piezoelectric coupled-field capabilities of the finite-element (FE) package Ansys/Multiphysics and simulation results were compared with the measurements of the real structures.     

Monitoring of Wear Characteristics of TiN and TiAlN Coatings at Long Sliding Distances

TiN and TiAlN thin hard coatings have been widely applied on machine components and cutting tools to increase their wear resistance. These coatings have different wear behaviors, and determination of their wear characteristics in high-temperature and high-speed applications has great importance in the selection of suitable coating material to application. In this article, the wear behavior of single-layer TiN and TiAlN coatings was investigated at higher sliding speed and higher sliding distances than those in the literature. The coatings were deposited on AISI D2 cold-worked tool steel substrates using a magnetron sputtering system. The wear tests were performed at a sliding speed of 45 cm/s using a ball-on-disc method, and the wear area was investigated at seven different sliding distances (36–1,416 m). An Al₂O₃ ball was used as the counterpart material. The wear evolution was monitored using a confocal optical microscope and surface profilometer after each sliding test. The coefficient of friction and coefficient of wear were recorded with increasing sliding distance. It was found that the wear rate of the TiAlN coating decreases with sliding distance and it is much lower than that of TiN coating at longer sliding distance. This is due to the Al₂O₃ film formation at high temperature in the contact zone. Both coatings give similar coefficient of friction data during sliding with a slight increase in that of the TiAlN coating at high sliding distances due to the increasing alumina formation. When considering all results, the TiAlN coating is more suitable for hard machining applications.     

Mechanical Testing and Finite Element Simulations for the Use of Cellular Metals as Car Seat Components

Due to the high energy absorption capacity at constant compressive stress level, cellular metals may be used as crash‐energy‐absorbing elements in autobody structures or car components, e.g., car seats. Modern car seats do not only have a high technical functionality, like electronic positioning, heating, and ventilation systems; in the case of a crash they must protect the passenger. The present paper deals with an analysis of potentially suitable cellular metals for integration in car seats. By means of different quasi‐static tests, i.e., compression, tensile, shear, and bending testing of several candidate metal foams and foam sandwich structures, the general material properties, the damage behavior and the reproducibility of mechanical data are tested. The results, which include optical 3D strain distribution measurements of the chosen cellular metals during quasi‐static testing, are implemented in the engineering design of structural car seat components and finite element calculations to simulate the crash behavior. Objective of the work is the derivation of robust and reliable mechanical testing procedures and standards as well as an improved understanding of the damage mechanisms of cellular metals under different loading conditions to finally derive design guidelines for cellular metals.     

Properties of Lead Zirconate Titanate Thick-Film Piezoelectric Actuators on Ceramic Substrates

Lead zirconate titanate (PZT) is a piezoelectric material that can sense or respond to mechanical deformations and can be used in ceramic electro-mechanical systems (C-MEMS). The microstructural, electrical, and piezoelectric characteristics of thick PZT films on low-temperature cofired ceramics (LTCC) and alumina substrates were studied. The PZT composition was prepared with low-melting-point additives in order to decrease the sintering temperature and to be compatible with thick-film technology. The integration of the PZT thick-film materials on ceramic substrates could lead to degradation of the PZT's characteristics due to the interactions between an active PZT layer and a substrate, particularly with glassy LTCC material. To minimize the interactions with LTCC substrates, an intermediate PZT barrier layer was integrated. The value of the piezoelectric coefficient d ₃₃ was found to be up to 120 pC/N on an alumina substrate and approximately 50 on an LTCC substrate. Based on these results, a cantilever-type actuator was designed and fabricated on alumina substrates. Under an applied voltage of 200 V, the maximum tip deflection was about 5 μm.     

Anonymous and secure electronic transaction protocol

We present a new protocol for electronic transactions which is not only secure but also anonymous, the latter characteristic being obtained by associating an encryption device with a chip card. Security is ensured by the use of encryption, electronic signature and authentication. In order to check the validity of the security properties enforced by the protocol, a model and a specification are provided. The protocol modeling language is a process algebra with value passing extended by an observation mechanism allowing the specification of security levels, by cryptographic primitives, and by a function call feature on private channels allowing the modeling of interactions with the crypto-system. The anonymity is expressed by an information flow property. The verification method, based on cosimulation, is proved consistent and complete and analysis confirms that this approach ensures not only anonymity (thanks to the fact that the client never discloses to the merchant any information permitting his identification), but also the quasi-impossibility of any fraudulent transaction.