High Energy Beam Processes Research Articles

Current and Future Trends for Polymer Micro/Nanoprocessing in Industrial Applications.

Polymers are widely used in optical devices, electronic devices, energy-harvesting/storage devices, and sensors, owing to their low weight, excellent flexibility, and simple fabrication process. With advancements in micro/nanoprocessing techniques and more demanding application requirements, it is becoming necessary to realize high-resolution fabrication of polymers to prepare miniaturized devices. This is particularly because conventional processing technologies suffer from high thermal stress and strong adhesion/friction, which can irreversibly damage the micro/nanostructures of miniaturized devices. In addition, although the use of advanced fabrication methods to prepare high-resolution micro/nanostructures is explored, these methods are limited to laboratory research or small-batch production. This review focuses on the micro/nanoprocessing of polymeric materials and devices with high spatial precision and replication accuracy for industrial applications. Specifically, the current state-of-the-art techniques and future trends for micro/nanomolding, high-energy beam processing, and micro/nanomachining are discussed. Moreover, an overview of the fabrication and applications of various polymer-based elements and devices such as microlenses, biosensors, and transistors is provided. These techniques are expected to be widely applied for multiscale and multimaterial processing as well as for multifunction integration in next-generation integrated devices, such as photoelectric, smart, and biodegradable devices.

Special Issue on Precision Surface Finishing

Precision surface finishing plays an important role in product quality owing to its direct effects on product appearance. As a result, automated precision surface finishing processes (APSFPs) are key technologies for industrial products and molds for forming and shaping processes. APSFPs can be divided into three main categories, namely, mechanical processes, electrochemical processes, and high energy beam processes. The objective of this special issue is to collect the cutting-edge research works focused on APSFPs. This issue includes 11 papers on APSFPs covering the following topics: ===danraku===- Review of ultraprecision surface finishing processes. ===danraku===- Ultraprecision surface machining and finishing with compensated feeding mechanisms. ===danraku===- Ultrasonic assisted cutting of unidirectional wetting surfaces and polishing of mold steels. ===danraku===- Vibration-assisted polishing of glass lenses. ===danraku===- Magnetic-assisted polishing of mirror surfaces. ===danraku===- Chemical-mechanical polishing of single-crystal SiC and GaN wafers. ===danraku===- Direct transfer of smoothing Au surfaces. ===danraku===- Plasma surface finishing of narrow channel walls of X-ray crystal monochromators. ===danraku===- Analysis and characterization of finished surfaces. It is expected that this issue will be helpful for readers to understand the recent developments in APSFPs and will lead to further research on APSFPs. We deeply appreciate the contributions of all authors and thank the reviewers for their incisive efforts.

II 溶接・接合プロセスとシステム化技術 2. 高エネルギービーム加工

II 溶接・接合プロセスとシステム化技術 2. 高エネルギービーム加工

Combination of high energy beam processing with thermochemical treatment and hard protective coating: state of the art

Abstract The state of the art in combining electron beam or laser surface processing with thermochemical surface treatment (nitriding, nitrocarburising, boronising) or physical vapour deposition/chemical vapour deposition hard coating (based on TiN, TiCN) is reviewed with reference to developments since 1980. The focus of the investigations reported was on steel substrates (C45; 31CrMoV9; 50CrV4; 100Cr6; X100CrMoV5-1, X155CrVMo12-1, X220CrVMo13-4). The relationships between treatment conditions, process parameters and structure, composition and properties of the layers, base material and composite are discussed. Combined surface heat treatment technologies are constantly opening up new fields for industrial application. Examples of cold forming and injection moulding tools and automotive components are described.

Modeling and Experimental Verification of Transient/Residual Stresses and Microstructure Formation in Multi-Layer Laser Aided DMD Process

Despite enormous progress in laser aided direct metal/material deposition (LADMD) process many issues concerning the adverse effects of process parameters on the stability of variety of properties and the integrity of microstructure have been reported. Comprehensive understanding of the transport phenomena and heat transfer analysis is essential to predict the thermally induced residual stresses and solidification microstructure in the deposited materials. Traditional solidification theories as they apply to castings or related processes, assume either no mass diffusion in the solid (Gulliver-Scheil) or complete diffusion in the solid (equilibrium lever rule) in a fixed arm space. These are inappropriate in high energy beam processes involving significantly high cooling rates. The focus of this paper is the solute transport in multi-pass LADMD process, especially the coupling of the process scale transport with the transport at the local scale of the solid-liquid interface. This requires modeling of solute redistribution at the scale of the secondary arm spacing in the dendritic mushy region. This paper is an attempt toward a methodology of finite element analysis for the prediction of solidification microstructure and macroscopic as well as microscopic thermal stresses. The computer simulation is based on the metallo-thermo-mechanical theory for uncoupled temperature, solidification, phase transformation, and stress/strain fields. The importance of considering phase transformation effects is also verified through the comparison of the magnitudes of residual stresses with and without the inclusion of phase transformation kinetics. The simulation has been carried out for H13 tool steel deposited on a mild steel substrate.

A new treatment of interface condition in temperature field calculation during high energy beam processing of materials

The temperature field of a metal substrate subjected to a high intensity scanning laser beam is numerically calculated with using the interface response function to determine the solid/liquid interface temperature along the solidification side of the melting pool. The calculated results show meaningful difference from that using a fixed temperature along the solid/liquid interface. The result is helpful in understanding some experimental phenomenon.

Correlation between solidification parameters and weld microstructures

AbstractSolidification behaviour controls the size and shape of grains, the microstructure, the extent of segregation, the distribution of inclusions, the extent of defects such as porosity and hot cracks, and ultimately the properties of weld metal. In the past, theories related to single crystal growth technology and the solidification of castings have been extrapolated to describe weld metal solidification. However, within the past two decades there have been several new developments in solidification theory. Furthermore, welding involving high energy beam processes and significantly greater cooling rates have received much emphasis. Traditional solidification theories as they apply to castings are not appropriate in describing solidification under these latter conditions. This paper provides a comprehensive review of the solidification behaviour of a weld pool incorporating recent advances in solidification theories. Basic principles from ingot, single crystal, and rapid solidification processes are u...