PREPARATION AND CHARACTERIZATION OF CaZrO3COATING ON GRAPHITE FOR TiNi ALLOY MELTING

Graphite is a favorable melting material of TiNi alloy. In order to reduce the carbon increment during high temperature process, the protective CaZrO3 coating has been prepared using different methods. First, CaZrO3 powder was synthesized via solid-state reaction using calcium metal as raw material. The coating on graphite was prepared by flame spraying, plasma spraying and dipping sintering, then it was observed and characterized. The results show that the apparent quality of the obtained coating is intactness. Here, the spraying coating is composition uniform and structure compact; the dipping coating exhibits an obvious color change and presents the typical porous structure.

Modelling and optimization of laser polishing of additive laser manufacturing surfaces

Purpose Direct metal deposition (DMD) with laser is an additive manufacturing process enabling rapid manufacturing of complex metallic and thin parts. However, the final quality of DMD-manufactured surfaces is a real issue that would require a polishing operation. Polishing processes are usually based on abrasive or chemical techniques. These conventional processes are composed by many drawbacks such as accessibility of complex shapes, environmental impacts, high time consumption and cost, health risks for operators, etc. […] This paper aims to solve these problems and improve surface quality by investigating the laser polishing (LP) process. Design/methodology/approach Based on melting material by laser, the LP process enables the smoothing of initial topography. However, the DMD process and the LP processes are based on laser technology. In this context, the laser DMD process is used directly on the same machine for the polishing operation. Currently, few studies focus on LP of additive laser manufacturing surfaces, and it tends to limit the industrial use of additive manufacturing technology. The proposed study describes an experimental analysis of LP surfaces obtained by DMD process. Findings The investigation results in the improvement of a complete final surface quality, according to LP parameters. For mastering LP processes, operating parameters are modelled. Originality/value This experimental study introduces the LP of thin and complex DMD parts, to develop LP applications. The final objective is to create a LP methodology for optimizing the final topography and productivity time according to parts’ characteristics.

Modeling the Reflow Soldering Process in PCB’s

In the present work two different types of case studies are modelled, carried out involving the fusing of a material using the CFD (Computational Fluid Dynamics) software Ansys Fluent, using the VOF method (Volume of Fluid) to capture the position of the existing interfaces and the Solidification/melting method which uses an enthalpy-porosity approach to simulate the fusion of the material. The first case focus itself in the analysis of fusing process and dropping behavior of the melted plate in the presence of a thermal source. The validation is made using a study found in the bibliography and then using water as the melting material given that its behavior is well known. Then tin is used as the melting material followed by the use of SAC 405 as the melting plate. This study compares various materials properties and verifies the influence of some of these particular properties by changing them (surface tension and heat of fusion). The second case focus on the simulation of a geometry obtained at balance at a constant temperature by the SAC 405 soldering alloy in the presence of a component and the copper substrate on top of a PCB.

Modeling and Optimization of Laser Polishing Process

Laser polishing is a finishing process based on melting material, with the objective of improving surface topography. Some operating parameters must be taken into consideration, such as laser power, feed rate, offset, and overlapping. Moreover, because of its dependence on the primary process, the initial topography has also an impact on the final result. This study describes a quadratic model, conceived to optimize final topography according to the primary process and laser polishing. Based on an experimental matrix, the model takes into account both laser operating parameters and the initial topography, in order to predict polished surfaces and to determine optimal set of parameters. After the phase of experimentation and the creation of the quadratic model, an optimal final topography is introduced, taking into account the initial surface and the laser parameters.

Study of the Effect of Feldspar Replacement from a Mixture of Glass / Syenite in Technological Properties of Ceramic Coatings

Obtaining new raw materials for the production of ceramic coating is increasingly highlighted, however, it is desirable to maintain or improve the technological properties of the formed product. Thinking about it, and aiming at the environmental context, the aim of this work is to study the mixing recycled glass effect with syenite, an alternative melting often used in the production of ceramic tiles, in replacing to feldspar. The raw materials were characterized and subsequently the technological properties were determined for the standard formulation and the formulations with 5, 10, 15 and 20% mixing glass / syenite, in replacing to feldspar. The test bodies were prepared by wet, and sintered at different temperatures, with a rate of 30 °C /min and a level of 20 minutes. The results indicate that the mixing glass / syenite has the potential to be used as melting material in the composition of the ceramic mass.

Lateral Extrusion of A6063 Pipes with a Lost Core of Alumina Powder Bonded with Wax

The authors have developed a lateral extrusion process with a lost core. The outline of the process is as follows. First, the cavity of a pipe, or a channel material, is filled up with liquid of a low-temperature melting material. The low-temperature melting material is then solidified to become a soluble core of the pipe. The authors call this soluble core the lost core. Next, the material is compressed longitudinally as a composite billet and extruded in the lateral direction. After deformation, the low-temperature melting material is melted and removed. The process can performed in a compression state to control the precise appearance of the product. This study examines a new core material, alumina powder (alumina ball) bonded with wax, as a core material. A mixing methodology for wax and alumina powder is discussed along with the effect of their mixing ratio on the deformation of the pipe.

Research on the Performance of Ultrasonic Vibration Assisted Electrical Discharge Surface Modification Layer

Ultrasonic vibration assisted electrical discharge surface modification was studied in the paper. The influence of ultrasonic vibration amplitude and frequency on the modification layer performance, such as surface roughness, sectional morphology, micro hardness and wear resistance was investigated. Experimental results show that ultrasonic vibration assisted electrical discharge surface modification can improve surface roughness and make the melting material well-distributed. The surfaces have higher micro hardness and wear resistance when the tool electrode is assisted with ultrasonic vibration.

An Investigation of Attachment on Electrode Surface in Dry EDM

Dry Electrical discharge machining (Dry EDM), using gas as dielectric, has been developed to solve problems against environment. It has both advantages of high material removal ratio (MRR) and low relative electrode wear ratio (REWR). We investigated the effect of duty factor, peak current, and reference ratio of gap voltage on MRR and REWR of Dry EDM, respectively. Moreover, trying to prove the attachment on electrode surface could decline REWR. It is considered that melting material of work-piece was sputtered and stuck onto electrode surface, and to become a protection layer as result in low REWR. However, the attachment will be removed under the condition of high peak current and high discharge frequency. But the amount of attachment just has little change when discharge number and arc discharge ratio are both decrease.