질화규소 세라믹의 레이저 예열선삭에 관한 연구 공정변수에 따른 질화규소의 예열특성 및 산화거동 김종도 † 이수진 서 정 이제훈 한국해양대학교 기관시스템공학부 한국해양대학교 대학원 한국기계연구원 광응용생산기계연구실 A Study on Laser Assisted Machining for Silicon Nitride Ceramics ( ) - Preheating Characteristics and Oxidation Behaviors of Silicon Nitride Ceramics with Machining Parameters - Jong-Do Kim* , † , Su-Jin Lee**, Jeong Suh*** and Jae-Hoon Lee*** *Division of Marine System Engineering, College of Maritime Sciences, Korea Maritime University, Busan 606-791, Korea ** Graduate School, Korea Maritime University, Busan 606-791, Korea *** Korea Institute of Machinery & Materials, Laser Application Team, Daejeon 305-343, Korea † Corresponding author : [email protected](Receive March 24, 2010 ; Revised April 13, 2010 ; Accepted May 17, 2010) Abstract Silicon nitride is widely used as an engineering ceramics because it has high strength, abrasion resistance and corrosion resistance even at high temperature. However, machining of silicon nitride is difficult due to its high hardness and brittleness. Laser assisted machining(LAM) allows effective cutting using CBN tool by locally heating the cutting part to the softening temperature of YSiAlON using the laser beam. The effect of preheating depending on process parameters were studied to find out the oxidation mechanism. If silicon nitride is sufficiently preheated, the surface is oxidized and N 2 gas is formed and escapes from the material, thereby making the cutting process more advantageous. During laser preheating process before machining, high temperature results in strong oxidation which makes the bloating, silicate layers and micro cracks. Using the results of these experiments, preheating characteristics and oxidation behavior were found out. Key Words : Silicon nitride, HPDL, LAM, Oxidation behavior, Machining parameters 1. 서 론 비약적인 기술의 발전에 힘입어 최근에는 기기의 수 명 및 관리에 대한 관심이 높아져 특수합금 스테인리 스강 플라스틱 및 세라믹과 같은 신소재에 관한 연구 가 지속되어 오고 있다 고품질 세라믹 재료는 중량대 비 고강도 우수한 내마모성 화학적 안정성 및 고온에 서의 고강도 유지와 같은 뛰어난 특성으로 건축 엔진 의료응용 항공 및 해양 분야 등 다양한 분야에서 널리 사용되고 주목을 받고 있다 그러나 고품질 세라믹의 고 강도 및 높은 취성이라는 재료적 특성으로 인하여 표면 결함 미소균열 표층하부의 손상 등이 쉽게 발생하여 재료를 제품으로 형상화하는 것이 어렵고 제품가공에 있어서 높은 비용 및 긴 가공시간을 요구하므로 여러 분야에서의 폭넓은 적용에 큰 제약이 뒤따르고 있다 따라서 본 논문에서는 레이저를 이용하여 세라믹을 국부적으로 가열하고 연화된 부분을 선삭하여 제거하는 연구논 문
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大韓熔接․接合學會誌 第28卷 第4號, 2010年 8月 415
61
질화규소 세라믹의 레이저 예열선삭에 관한 연구 (Ⅰ)- 공정변수에 따른 질화규소의 예열특성 및 산화거동 -
김종도*,†․이수진
**․서 정
***․이제훈
***
*한국해양대학교 기관시스템공학부
**한국해양대학교 대학원
***한국기계연구원 광응용생산기계연구실
A Study on Laser Assisted Machining for Silicon Nitride Ceramics (Ⅰ)- Preheating Characteristics and Oxidation Behaviors of Silicon Nitride Ceramics with Machining Parameters -
Jong-Do Kim*,†, Su-Jin Lee**, Jeong Suh*** and Jae-Hoon Lee***
*Division of Marine System Engineering, College of Maritime Sciences, Korea Maritime University, Busan 606-791, Korea
** Graduate School, Korea Maritime University, Busan 606-791, Korea*** Korea Institute of Machinery & Materials, Laser Application Team, Daejeon 305-343, Korea
†Corresponding author : [email protected](Receive March 24, 2010 ; Revised April 13, 2010 ; Accepted May 17, 2010)
Abstract
Silicon nitride is widely used as an engineering ceramics because it has high strength, abrasion resistance and corrosion resistance even at high temperature. However, machining of silicon nitride is difficult due to its high hardness and brittleness. Laser assisted machining(LAM) allows effective cutting using CBN tool by locally heating the cutting part to the softening temperature of YSiAlON using the laser beam. The effect of preheating depending on process parameters were studied to find out the oxidation mechanism. If silicon nitride is sufficiently preheated, the surface is oxidized and N2 gas is formed and escapes from the material, thereby making the cutting process more advantageous. During laser preheating process before machining, high temperature results in strong oxidation which makes the bloating, silicate layers and micro cracks. Using the results of these experiments, preheating characteristics and oxidation behavior were found out.