Research on Elastic-Plastic Transition and Hardening Effect for Monocrystalline Silicon Surfaces

2014 ◽  
Vol 1027 ◽  
pp. 101-106
Author(s):  
Xiao Guang Guo ◽  
Chang Heng Zhai ◽  
Zi Yuan Liu ◽  
Liang Zhang ◽  
Zhu Ji Jin ◽  
...  
Keyword(s):  
High Frequency ◽  
Crystal Surface ◽  
Silicon Crystal ◽  
Silicon Surfaces ◽  
Precision Machining ◽  
Displacement Curve ◽  
Elastic Plastic ◽  
Ultra Precision ◽  
Load Displacement ◽  
Dynamics Method

Based on molecular dynamics method, a nanoindentation simulation of the silicon crystal is built and the load-displacement curve is drawn. According to the load-displacement curve, the elastic-plastic transition of silicon crystal is analyzed. The results show that the critical point in the elastic-plastic transition is between 15 and 20 angstroms. In addition, different crystal planes of silicon crystal are loaded for five cycles respectively; the nanohardness is calculated and the nanohardness curve is obtained. The results show that after the first plastic deformation of the silicon crystal surface is occurred, the surface will have a higher hardness and a higher elasticity. Therefore, in the ultra precision machining, in order to reduce the occurrence of damage, the depth of the processing should be controlled in the range of elasticity. Moreover, the method of small quantities in high frequency can increase mechanical properties on the surface.

Effect of Hydrogen on the Mechanical Properties of Silicon Crystal Surface

2013 ◽  
Author(s):  
Hayato Izumi ◽  
Ryota Mukaiyama ◽  
Nobuyuki Shishido ◽  
Shoji Kamiya
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Crystal Surface ◽  
Silicon Crystal ◽  
Single Crystal Silicon ◽  
Displacement Curve ◽  
Hydrogen Atoms ◽  
Crystal Silicon ◽  
Boron Doped ◽  
Energy Dissipated

This paper reports the mechanical properties of single crystal silicon surface changed with hydrogen atoms trapped by underwater boiling treatment. Nanoindentaion test using a Berkovich indenter in six different indentation loads ranging from 100 μN to 1000 μN was conducted to obtain the load-displacement curve. The energy dissipated in plastic deformation, i.e. plasticity energy, during indentation on silicon wafers with different carrier concentration (undoped, lightly and heavily boron doped silicon) were compared. After boiling treatment, increment in the plasticity energy was observed on silicon containing boron. This result suggests that hydrogen atoms trapped inside silicon enhanced dislocation mobility leading to larger plastic deformation.

Study on Ultra-Precise Machining of CLBO Crystal

2006 ◽  
Vol 304-305 ◽  
pp. 398-402 ◽  
Author(s):  
Xun Lv ◽  
Ju Long Yuan ◽  
Yong Dai ◽  
Jia Jin Zheng ◽  
Zhao Zhong Zhou ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Quality ◽  
Crystal Surface ◽  
Technical Problem ◽  
Damage Threshold ◽  
Laser Wavelength ◽  
Precision Machining ◽  
Lithium Borate ◽  
Fundamental Laser ◽  
Ultra Precision

Cesium Lithium Borate (CsLiB6O10 or CLBO) is the most effective non-linear crystal which generates ultraviolet harmonics of the Nd:YAG fundamental laser wavelength. In order to enhance the damage threshold, low CLBO surface roughness, by ultra-precision machining, is needed. Because the CLBO crystal has easy hydroscopic reaction and micro scratches in machining, ultra-precise machining of the CLBO crystal is a difficult technical problem. In this paper, the new lapping slurry and polishing slurry are introduced. And the deliquescence degree of CLBO is fallen to lowest. A new working technology is also adopted. After rough polishing, the concentration of ultra-precision polishing slurry is increased properly. So does the ultra-precision polishing speed, and the wiping speed is faster than the deliquescence speed. The CLBO crystal surface roughness can achieve 1nm and keep the surface quality well.

Dynamics Model of Micro-Displacement Stage Based on High-Frequency

2014 ◽  
Vol 625 ◽  
pp. 167-171
Author(s):  
Huan Wei Zhou ◽  
Xin Chen ◽  
Xin Du Chen ◽  
Ke Tian Li
Keyword(s):  
High Frequency ◽  
Frequency Control ◽  
Free Form ◽  
Precision Machining ◽  
Machining Accuracy ◽  
Experimental Conditions ◽  
Depth Study ◽  
Ultra Precision ◽  
Motion Characteristics ◽  
Micro Structures

The optical structure has a large number of micro-structures, which has multiple arrays, complex free-form surface features. But those can not be achieved the requirements with traditional turning and grinding processing, it require to use high-frequency and micro-feed to get ultra-precision machining precision. After creating the 3D digital model of micro-displacement platform using Pro/Engineer, and analyzing the motion and the force, the paper studies the influencing factors about the rigidity and acceleration and explores the motion characteristics of the micro-displacement platform in the high-frequency control, and it the establishes the corresponding dynamics equation. The stiffness and linearity data is accessed after the micro-stage is simulated used by Admas and Ansys software. According to the above data, the structure of micro-stage is optimized in order to meet the ultra-precision machining accuracy and the quality of the workpiece. The research takes advantage of the favorable conditions of the Nanofabrication Laboratory, and it has completed the physical production of the micro-displacement platform supported by the introduction of innovative R&D team program of Guangdong Province, those provide a reliable experimental conditions for future in-depth study.

Ultrasonic Elliptical Vibration Turning Studty for Precision and Ultra-Precision Workpiece

2011 ◽  
Vol 189-193 ◽  
pp. 3-8
Author(s):  
Wen Li ◽  
Lin Song Yan ◽  
De Yuan Zhang
Keyword(s):  
Surface Roughness ◽  
High Frequency ◽  
Small Amplitude ◽  
Precision Machining ◽  
Machining Efficiency ◽  
Elliptical Vibration Cutting ◽  
Vibration Cutting ◽  
Elliptical Vibration ◽  
Ultra Precision ◽  
Ultrasonic Elliptical Vibration

Based on ultrasonic elliptical vibration cutting (UEVC) model, kinematical formulas of elliptical vibration cutting(EVC) is established, the paper presented relationship of vibration parameters effecting on surface roughness, machining accuracy and machining efficiency, revealed UEVC characteristics of high frequency and small amplitude are more conducive to improve surface roughness, advance EVC machining efficiency. Experiences of cutting the weak rigidity workpiece by the designed adjusting frequency elliptical transducer is proved that compared conventional turning, increasing vibration frequency and decreasing amplitude are result in improve surface roughness, and compared low frequency EVC, decrease amplitude are result in reduce the height of vibration ripples in cutting direction, and advance machining efficiency. So high frequency and small amplitude EVC is more conducive to precision machining and ultra-precision machining.

scholarly journals A Self-Established “Machining-Measurement-Evaluation” Integrated Platform for Taper Cutting Experiments and Applications

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 929
Author(s):  
Xudong Yang ◽  
Zexiao Li ◽  
Linlin Zhu ◽  
Yuchu Dong ◽  
Lei Liu ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Precision Machining ◽  
Two Dimensional ◽  
Dimensional Image ◽  
Two Dimensional Image ◽  
Integrated Platform ◽  
Hard And Brittle Materials ◽  
Ultra Precision ◽  
Cutting Experiments

Taper-cutting experiments are important means of exploring the nano-cutting mechanisms of hard and brittle materials. Under current cutting conditions, the brittle-ductile transition depth (BDTD) of a material can be obtained through a taper-cutting experiment. However, taper-cutting experiments mostly rely on ultra-precision machining tools, which have a low efficiency and high cost, and it is thus difficult to realize in situ measurements. For taper-cut surfaces, three-dimensional microscopy and two-dimensional image calculation methods are generally used to obtain the BDTDs of materials, which have a great degree of subjectivity, leading to low accuracy. In this paper, an integrated system-processing platform is designed and established in order to realize the processing, measurement, and evaluation of taper-cutting experiments on hard and brittle materials. A spectral confocal sensor is introduced to assist in the assembly and adjustment of the workpiece. This system can directly perform taper-cutting experiments rather than using ultra-precision machining tools, and a small white light interference sensor is integrated for in situ measurement of the three-dimensional topography of the cutting surface. A method for the calculation of BDTD is proposed in order to accurately obtain the BDTDs of materials based on three-dimensional data that are supplemented by two-dimensional images. The results show that the cutting effects of the integrated platform on taper cutting have a strong agreement with the effects of ultra-precision machining tools, thus proving the stability and reliability of the integrated platform. The two-dimensional image measurement results show that the proposed measurement method is accurate and feasible. Finally, microstructure arrays were fabricated on the integrated platform as a typical case of a high-precision application.

scholarly journals An Investigation of the Cutting Strategy for the Machining of Polar Microstructures Used in Ultra-Precision Machining Optical Precision Measurement

Micromachines ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 755
Author(s):  
Chen-Yang Zhao ◽  
Chi-Fai Cheung ◽  
Wen-Peng Fu
Keyword(s):  
Precision Measurement ◽  
Detection Algorithm ◽  
Surface Generation ◽  
Precision Machining ◽  
Tool Geometry ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
Ultra Precision ◽  
Transition Points ◽  
Cutting Strategy

In this paper, an investigation of cutting strategy is presented for the optimization of machining parameters in the ultra-precision machining of polar microstructures, which are used for optical precision measurement. The critical machining parameters affecting the surface generation and surface quality in the machining of polar microstructures are studied. Hence, the critical ranges of machining parameters have been determined through a series of cutting simulations, as well as cutting experiments. First of all, the influence of field of view (FOV) is investigated. After that, theoretical modeling of polar microstructures is built to generate the simulated surface topography of polar microstructures. A feature point detection algorithm is built for image processing of polar microstructures. Hence, an experimental investigation of the influence of cutting tool geometry, depth of cut, and groove spacing of polar microstructures was conducted. There are transition points from which the patterns of surface generation of polar microstructures vary with the machining parameters. The optimization of machining parameters and determination of the optimized cutting strategy are undertaken in the ultra-precision machining of polar microstructures.

scholarly journals Study on the Strength Performance of Recycled Aggregate Concrete with Different Ages under Direct Shearing

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2312
Author(s):  
Xin Liang ◽  
Fang Yan ◽  
Yuliang Chen ◽  
Huiqin Wu ◽  
Peihuan Ye ◽  
...  
Keyword(s):  
Shear Strength ◽  
Shear Force ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Displacement Curve ◽  
Direct Shear ◽  
Replacement Ratio ◽  
Aggregate Concrete ◽  
Concrete Failure ◽  
Load Displacement

In order to study the mechanical properties of recycled aggregate concrete (RAC) at different ages, 264 standard cubes were designed to test its direct shear strength and cube compressive strength while considering the parameters of age and recycled aggregate replacement ratio. The failure pattern and load–displacement curve of specimens at direct shearing were obtained; the direct shear strength and residual shear strength were extracted from the load–displacement curves. Experimental results indicate that the influence of the replacement ratio for the front and side cracks of RAC is insignificant, with the former being straight and the latter relatively convoluted. At the age of three days, the damaged interface between aggregate and mortar is almost completely responsible for concrete failure; in addition to the damage of coarse aggregates, aggregate failure is also an important factor in concrete failure at other ages. The load–displacement curve of RAC at direct shearing can be divided into elasticity, elastoplasticity, plasticity, and stabilization stages. The brittleness of concrete decreases with its age, which is reflected in the gradual shortening of the elastoplastic stage. At 28 days of age, the peak direct shear force increases with the replacement ratio, while the trend is opposite at ages of 3 days, 7 days, and 14 days, respectively. The residual strength of RAC decreases inversely to the replacement ratio, with the rate of decline growing over time. A two-parameter RAC direct shear strength calculation formula was established based on the analysis of age and replacement rate to peak shear force of RAC. The relationship between cube compressive strength and direct shear strength of recycled concrete at various ages was investigated.

A novel method to determine critical CTOA directly by load-displacement curve

2020 ◽  
Vol 230 ◽  
pp. 107013
Author(s):  
Ying Zhen ◽  
Xuyang Li ◽  
Yuguang Cao ◽  
Shihua Zhang
Keyword(s):  
Displacement Curve ◽  
Novel Method ◽  
Load Displacement
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