본 논문에서는 지오폴리머의 상변화를 관찰하기 위하여 나노인덴테이션 데이터를 가우시안 믹스쳐 모델로 분석하는 방법을 제시 하였다. 지오폴리머는 일반 시멘트 대비 CO2 발생량을 줄일 수 있어 시멘트 대체 재료로써 많은 연구가 이루어지고 있다. 기존 연구들 로부터 최적의 실리콘/알루미늄 비율을 찾았으나 1.8 초과에서 압축강도 저하의 원인은 아직 불분명하다. 본 연구에서는 실리콘/알루 미늄 비율이 재료에 미치는 영향을 조사하고자 나노인덴테이션 실험을 수행하였다. 실험 결과를 가우시안 믹스쳐 모델로 상분석하였 고, 실리콘/알루미늄 비율이 증가할수록 재료가 균질거동을 하는 것을 관찰할 수 있었다. 본 연구결과는 강도저하를 규명하는데 직접 적인 근거로 활용될 수 있을 것으로 기대된다.

Stress-strain curves are fundamental properties to study characteristics of materials. Flow stress curves of the powder materials are obtained by indirect testing methods, such as tensile test with the bulk materials and powder compaction test, because it is hard to measure the stress-strain curves of the powder materials using conventional uniax- ial tensile test due to the limitation of the size and shape of the specimen. Instrumented nanoindentation can measure mechanical properties of very small region from several nanometers to several micrometers, so nanoindentation tech- nique is suitable to obtain the stress-strain curve of the powder materials. In this study, a novel technique to obtain the stress-strain curves using the combination of instrumented nanoindentation and finite element method was introduced and the flow stress curves of Fe powder were measured. Then obtained stress-strain curves were verified by the com- parison of the experimental results and the FEA results for powder compaction test.

In this study, the feasible test for the mechanical property characterization of ceramics and multi-layer ceramic capacitor(MLCC) was performed with nanoindentation technique. In case of ceramics, hardness and elastic modulus are dependent on the densification of specimen showing the highest hardness and elastic modulus values of 12.3 GPa and 155 GPa, respectively at . In case of MLCC chip, hardness of dielectric layer was lower than that of margin region. The nanoindentation method could be useful tool for the measurement of mechanical property within dielectric layer of very thin thickness in high capacitance MLCC

The indentation technique has been one of the most commonly used techniques for the measurement of the mechanical properties of materials due to its experimental ease and speed. Recently, the scope of indentation has been enlarged down to the nanometer range through the development of instrumentations capable of continuously measuring load and displacement. In addition to testing hardness, the elastic modulus of submicron area could be measured from an indentation load-displacement (P-h) curve. In this study, the hardness values of the constituent phases in Ti()-NbC-Ni cermets were evaluated by nanoindentation. SEM observation of the indented surface was indispensable in order to separate the hardness of each constituent phase since the Ti()-based cermets have relatively inhomogeneous microstructure. The measured values of hardness using nanoindentation were GPa for hard phase and GPa for binder phase. The effect of NbC addition on hardness was not obvious in this work.