CAJ | 학술논문

硬薄膜往往具有较脆的特性，在过载时易发生脆性断裂。本文研究了硬薄膜/软基体在锥形纳米压头作用下的断裂模式。利用等离子体化学沉积法在聚二醚酮基体上沉积生成类金刚石薄膜。使用纳米压痕法对其进行实验研究，实时记录纳米压头压入样品过程中所受的载荷以及位移。载荷位移曲线中有若干间断点，代表着裂纹的形成和扩展。压痕实验完成后，通过扫描电子显微镜和聚焦离子束观察发现，类金刚石薄膜压痕处出现规则的贯穿厚度的环形裂纹和径向裂纹。最后，利用有限元法分析了硬薄膜/软基体在锥形压头作用下的应力分布，通过cohesive单元模拟环形裂纹的起始和扩展。结果表明：环形裂纹是由薄膜表面较高的径向拉应力引起的，较高的径向拉应力发生于压头和薄膜表面接触区域的外侧；径向裂纹则是由薄膜在界面附近较大的拉应力引起的。并且，各圈环形裂纹的半径基本呈线性递增，这和实验观测基本相符。
경박막왕왕구유교취적특성，재과재시역발생취성단렬。본문연구료경박막/연기체재추형납미압두작용하적단렬모식。이용등리자체화학침적법재취이미동기체상침적생성류금강석박막。사용납미압흔법대기진행실험연구，실시기록납미압두압입양품과정중소수적재하이급위이。재하위이곡선중유약간간단점，대표착렬문적형성화확전。압흔실험완성후，통과소묘전자현미경화취초리자속관찰발현，류금강석박막압흔처출현규칙적관천후도적배형렬문화경향렬문。최후，이용유한원법분석료경박막/연기체재추형압두작용하적응력분포，통과cohesive단원모의배형렬문적기시화확전。결과표명：배형렬문시유박막표면교고적경향랍응력인기적，교고적경향랍응력발생우압두화박막표면접촉구역적외측；경향렬문칙시유박막재계면부근교대적랍응력인기적。병차，각권배형렬문적반경기본정선성체증，저화실험관측기본상부。
This article reports fracture in hard films on a soft substrate under conical indentation. A diamond-like carbon ( DLC) film was deposited onto a poly-ether-ether-ketone ( PEEK) substrate using plasma chemical vapor deposition. Nanoindentation was per-formed on the film surface, in the meanwhile, load and depth data were recorded, and‘pop-in', correlated with crack formation, was found in load-depth curves. Ring cracks and radial cracks in the film were observed by scanning electron microscopy and focused ion beam method after indentation. Finally, finite element analysis using cohesive elements was conducted to study the stress distribution of the hard film/soft substrate. It is found that ring cracks in the thin film are induced by high tensile radial stress on the film surface out-side the contact region of the indenter, while radial cracks are caused by high tensile stress on the thin film near the interface. The re-sults also show that the radius of ring cracks increases with the number of ring cracks, which agrees well with experimental observa-tions.