Hidetsugu Yagi

Preparation of DLC films using microwave plasma CVD in open-air

Diamond-like carbon films (DLC) were deposited on both the Si(100) and stainless steel substrate by means of Microwave Plasma enhanced chemical vapor deposition (PECVD) under the open-air. From the XPS measurements, the sp2/(sp2+sp3) ratio of the DLC film is similar to that of the film grown by the conventional PECVD. In the pulse-modulated microwave PECVD growth at the duty ratio 30%, the impurity incorporation into the film reduced.

Response of Student to the Introduction of CAD in Design Education

工学教育(J.of JSEE), 62–5(2014) 1.はじめに 機械工学は,根源的には「ものづくり」に関係する 学問であり,この過程において,「形状を決めること」 が重要な作業(製図)となる.機械系学科では,4分 野の力学(材料力学,熱力学,流体力学,機械力学) が中心的な科目として位置付けられている.これら4 分野の基礎を学習した後に,それぞれの分野ごとにテ ーマを設定し製図を行っていた.このような位置付け で,製図は機械工学の教育課程において古くから行わ れてきた講義であるが,近年のコンピュータの発達に 伴い急速に様相が変化してきた. コンピュータ支援設計(CAD)の導入以前は,まず 製図通則を覚え,次に具体的に幾つかの例題に沿って 手書きで描くことにより,2次元図面から3次元立体 をイメージする能力を養ってきた.2D-CADでは,3 次元の完成品を平面状に正確に投影して伝えるのが主 眼であった.言わば,手書きの製図をモニター上で行 っているのに過ぎなかった.しかし,3D-CADでは, マスプロパティ(体積,断面2次モーメントなど)と 呼ばれる形状情報を利用できるようになり,格段に高 度な設計ができるようになった.さらに,コンピュー タ上で立体を作成するプロセスそのものが2D-CAD と大きく異なる.また,1つの図面であってもデータ 間の関連が多岐にわたり,それらの管理が必要となる. CADを利用した教育については,カリキュラムの検 討と,3D-CADの具体的な活用事例が報 告されている.また,3D-CADを利用したテキスト も出版され教育環境が整ってきた. 最近の3D-CADソフトウェアでは,3次元立体が 完成すると2次元図面が出力できるようになってい る.手書きによる製図とCADによるものとのギャップ は2D-CADのときより一層大きくなってきた.この ことにより,手書きによる製図に対して学生の認識が 教員のそれとは異なっている可能性がある.特に,学 生が「手書きによる製図が中心となる低学年の製図」 を軽視していないか心配される.また,CADを学習し た後の授業において,CADの授業内容がどの程度役立 っているのか気になる所である.学期末に実施してい る「授業改善のためのアンケート調査」では,当該授 業に対する意見を調べることができるが,授業間の関 連性や過去にさかのぼった評価は現われ難い.そこで, 製図関係の授業を全て終えた愛媛大学工学部機械工学 科4年生を対象としてCAD教育に関連した内容のア ンケート調査を行った.

Preparation of hard carbon films by microwave plasma torched under the open-air

Summary form only given. In recent days, plasma phenomena and its process under atmospheric pressure (760 Torr) have been widely researched. The plasma process under atmospheric pressure is expected to be high speed in deposition and etching in spite of its controllability. If the process under atmospheric pressure realizes in the open-air, the processing system becomes simple and the controllability of substrates such as the processing area and the handling of substrates and the processing rate also becomes high in the open-air process. This enhances the availability of plasma process under atmospheric pressure. In this experiment, we deposited diamond and DLC (Diamond-like-Carbon) films by the plasma CVD process under entire open-air.

Diamond thin film preparation by microwave plasma chemical vapor deposition under the open-air condition

A diamond thin film has many attractive properties such as high hardness, large heat conductivity etc. Microwave plasma chemical vapor deposition (MWPCVD) is an effective method for producing a diamond thin film. However, the deposition rate of the conventional low-pressure MWPCVD is very low. Recently, the authors have succeeded to produce a diamond thin film on a Si substrate with high deposition rate (∼100m/h) under the open-air condition, i.e. under the atmospheric pressure and without chamber, using microwave plasma system with a torch (electrode) of coaxial structure. Since the system has open-air structure, vacuum system is not required, which results low cost. However, the stable deposition condition for both high deposition rate and high film quality has not established. In this study, the effect of the gap distance between the electrode and the substrate is studied experimentally to find the best condition for high quality diamond thin film preparation.

A New Measurement and Evaluation of Wettability between Solid and Liquid Metals in Ultra-High Vacuum. (2nd Report). Experimental Examination of Wettability and Atomic Diffusion.

This paper presents experimental results of the wettability and atomic diffusibility of liquid metals on clean solid surfaces. Six types of liquid metals; Au, Ag, Cu, Al, Fe, Ti, and three types of substrates; tungsten, glass-like carbon, highly oriented pyrolytic graphite (HOPG), are used as the specimens. Contact angles of liquid metals are measured with good reproducibility using a continuous Ar sputter cleaning process as is introduced in the previous paper. Interaction energies of these systems are obtained. As liquid Fe has different diffusibility for two carbon substrates, glass-like carbon and HOPG substrates, atomic concentrations of the substrate surfaces are investigated using scanning Auger electron spectroscopy. Consequently, it is found that liquid Fe has atomic diffusibility with a glass-like carbon surface but not with HOPG (001) surface.

An explanation of the wetting and the mutual diffusion mechanisms of liquid metals using ab-initio atomic orbital calculation

In this report, in order to clarify fundamentally the wetting phenomenon between pure material surfaces, we propose a new method for the experimental evaluation and consider quantitatively the wetting mechanism from the microscopic standpoint of the chemical reaction between interfacial atoms. Ab-initio molecular orbital calculation was performed to explain the wetting and the mutual diffusion mechanisms. It was found that the calculated binding energies were in good agreement with the interaction energies estimated from measured contact angles, and it was also cleared that the hybridization of the interfacial d-orbitals was one of the most important elements of the mutual diffusion.

Fatigue Strength of Copper-Infiltrated Sintered Iron Compacts

This study was undertaken to examine the influence of filling pore with copper on the fatigue strength of copper-infiltrated sintered iron compacts by means of microscopical observation of the aspects of its fatigue fracture under low and high cycles.The following conclusions are obtained from the investigation.1) The tensile strength of copper-infiltrated sintered iron compacts exhibits the same value irrespective of green porosity by filling pore with copper in the same sintering condition.2) In copper-infiltrated sintered iron compacts, the inflection point of the S-N curve is not clearly observed, and the curve is similar to that in cast iron, and the fatigue strength for the time rises differently from S-N curve of sintered iron compacts.3) The fatigue strength of copper-infiltrated sintered iron compacts is not influenced by the green porosity under low cycles.Under high cycles, the fatigue strength of the test pieces with the green porosity of 15% has the same value, but for the specimens with the green porosity over 15%, it falls as well as the sintered iron compacts, due to the difference in the shape of infiltrated copper.

The Relationship between the Pore Structure and the Mechanical Properties of the Sintered Iron Compacts

Sintered iron compacts have many pores, which seem to reduce the mechanical properties of them. The pore structure is very complex, and its influences on the mechanical properties are also complicated.Then, authors analyzed the pore structure, particularly size, shape, and distribution, quantitatively, and its effects on the mechanical properties were investigated.The following conclusions are obtained:1) The size of pore becomes large in proportion as the porosity increases, and in a case of the same porosity, the pore size becomes large as the particle size of iron powder is large.The shape of pore becomes irregular in proportion as the porosity increases.2) Tensile strength decreases with increasing porosity, but in a case of the same porosity, the strength is not much influenced with particle size of iron powder.On the other hand, fatigue strength varies not only with the porosity but also the particle size. This is considered to be caused by the characteristics of the mechanism of fatigue fracture.