The material removal mechanism of aluminate magnesium spinel was investigated by nanoindentation and microscratch test. The hardness increases with the increase of load. The influence of scratch speed and scratch load on the removal mechanism of spinel was analyzed based on the penetration depth, tangential force and acoustic emission (AE) signal. It was found that with the increase of scratch speed, the area of elastic-plastic removal and brittle plastic transition increased. The AE signal appears at the beginning of a brittle plastic transition for the first time. Moreover, the tangential force growth rate of spinel in the elastic-plastic stage is lower than that in the brittle removal stage. The results indicated that improving scratch speed and reducing the scratch load is beneficial to reduce the range of brittle removal of spinel, thus increasing the range of plastic removal and brittle plastic transition.
The gap average voltage measurement method is commonly used to detect the discharge state in micro electrical discharge machining (Micro-EDM), which is simple and effective for the discharge states detection of transistor pulse power and relaxation type pulse power. In order to further explore the ultimate machining ability of micro-EDM, a very high frequency (VHF, frequency range 30MHz~300MHz) micro energy pulse generator based on the principle of circuit resonance has been developed in a previous study. It has smaller discharge energy and nanoscale discharge erosion ability compared with the traditional pulse power. Furthermore, defects in micro-EDM such as thermal damage, recast layer and heat affected zone are significantly reduced. A simulation circuit model was established to analyze the effect of the gap average voltage measurement method applied to VHF pulse generator. The results show that the inter-electrode discharge states cannot be distinguished effectively and sensitively by this means. In order to detect the discharge state of VHF pulse generator, a novel method to detect discharge state based on impedance change of inter-electrode channel was presented, which is not affected by the pulse power. Hence, when the detection circuit was fixed, the detection sensitivity and the accuracy of threshold voltage was not varied according to different pulse parameters. Both simulation and experimental studies were undertaken to verify the effectiveness of the proposed method. The results demonstrate that the discharge states of VHF pulse generator can be distinguished by this detection method.
Potassium dihydrogen phosphate (KDP) is the irreplaceable nonlinear single crystal as optical frequency conversion and electro-optical switch in inertial confinement fusion (ICF) laser system. Based on the water solubility characteristics of KDP crystal, we propose an abrasive-free jet polishing (AFJP) method for KDP crystal with the purpose of improving surface quality without the embedding of particles. According to the AFJP experimental results, the jet spot generated by AFJP is of an approximately Gaussian shape. The feasibility of this approach has been studied through spot experiments. And the material removal mechanisms can be divided into contact removal and slipping removal.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.