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Processing Technology of Brittle Crystal Materials

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A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Polycrystalline Ceramics".

Deadline for manuscript submissions: closed (20 November 2022) | Viewed by 22288

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Special Issue Editors

Dr. Chen Li

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Guest Editor

School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, China
Interests: ultra-precision machining; grinding; composite energy field manufacturing; laser; close-to-atomic manufacturing
Special Issues, Collections and Topics in MDPI journals

Dr. Chongjun Wu

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Guest Editor

College of Mechanical Engineering, Donghua University, Shanghai 201620, China
Interests: high-performance machining; grinding mechanism; brittle materials; micro-nano additive manufacturing
Special Issues, Collections and Topics in MDPI journals

Dr. Binbin Meng

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Guest Editor

School of Future Science and Engineering, Soochow University, Suzhou 215000, China
Interests: grinding; SiC; diamond; multi-scale simulation
Special Issues, Collections and Topics in MDPI journals

Dr. Shanshan Chen

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Guest Editor

School of Mechanical Engineering, Xi'an Jiaotong University, 28 Xianning West Road, Xi'an 710049, China
Interests: ultra-precision machining; grinding; polishing; optics; ceramics

Special Issue Information

Dear Colleagues,

Brittle crystals and ceramics have been widely used in aerospace, 5G networks, and new energy vehicles owing to their excellent mechanical properties and stable chemical properties. For these advanced applications, brittle crystals and ceramics must be shaped into smooth substrates with high surface integrity using precision and ultra-precision processing technologies such as grinding, lapping, and polishing. However, there materials have high brittleness and hardness but low fracture toughness, posing great challenges for efficient machining. Brittle damages, including fractures and cracks, are easily generated during the machining process, which inevitably shortens the service life of crystal components and compromises further applications. Understanding the mechanical properties, revealing the damage evolution and material removal mechanism at micro- and nano-scales, exploring innovative machining technology, and optimizing machining process parameters are of great significance to realize the high-efficiency and precision machining of brittle materials. This collection aims to summarize the frontier research on processing and surface integrity characterization of brittle crystals, ceramics, glasses, and composite materials. The scope of this Special Issue includes but is not limited to:

Precision machining technology of brittle materials, such as grinding, polishing, lapping, etc.
In-depth characterization to reveal damage evaluation and removal behaviours involved in machining processes.
Numerical simulation of material deformation and removal processes.
Surface engineering when it relates specifically to a manufacturing process.

Dr. Chen Li
Dr. Chongjun Wu
Dr. Binbin Meng
Dr. Shanshan Chen
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Crystals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

crystal processing
grinding
polishing
cutting
single crystal
polycrystalline
ceramics
composite materials

Published Papers (12 papers)

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Research

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18 pages, 8860 KiB

Open AccessArticle

Mechanical Characteristics Generation in the Workpiece Subsurface Layers through Cutting

by Michael Storchak

Crystals 2023, 13(5), 761; https://doi.org/10.3390/cryst13050761 - 03 May 2023

Cited by 1 | Viewed by 1043

Abstract

The cutting process generates specific mechanical characteristics in the subsurface layers of the shaped parts. These characteristics have a decisive influence on the working properties and product durability of these parts. The orthogonal cutting process of structural heat-treated steel’s effect on the mechanical properties of the machined subsurface layers was evaluated by instrumented the nanoindentation method and sclerometry (scratch) method. As a result of this study, the relationship between the specific work in the tertiary cutting zone and the total deformation work during indenter penetration during the instrumented nanoindentation was established. The dependence of the indenter penetration depth during sclerometry of the machined subsurface layers of the workpiece was also studied. The orthogonal cutting process was carried out at different cutting speeds and tool rake angles. The cutting speed increase and the increase in the tool rake angle cause an increase in the indenter penetration work during the instrumented nanoindentation and an increase in the maximum indenter penetration depth during sclerometry. Simultaneously, the measured microhardness of the machined surfaces decreases with both an increase in cutting speed and an increase in the tool rake angle. Full article

(This article belongs to the Special Issue Processing Technology of Brittle Crystal Materials)

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13 pages, 3493 KiB

Open AccessArticle

Study on the Surface Generation Mechanism during Ultra-Precision Parallel Grinding of SiC Ceramics

by Shanshan Chen, Shuming Yang, Chi Fai Cheung, Tao Liu, Duanzhi Duan, Lai-ting Ho and Zhuangde Jiang

Crystals 2023, 13(4), 646; https://doi.org/10.3390/cryst13040646 - 09 Apr 2023

Cited by 1 | Viewed by 1850

Abstract

Silicon carbide (SiC) is a typical, difficult-to-machine material that has been widely used in the fabrication of optical elements and structural and heat-resistant materials. Parallel grinding has been frequently adopted to produce a high-quality surface finish. Surface generation is a vital issue for assessing surface quality, and extensive modeling has been developed. However, most of the models were based on a disc wheel with a cylindrical surface, whereas the surface topography generation based on an arc-shaped tool has been paid relatively little attention. In this study, a new theoretical model for surface generation in ultra-precision parallel grinding has been established by considering the arc-shaped effect, synchronous vibration of the wheel, and cutting profile interference in the tool feed direction. Finally, the ground surface generation mechanism and grinding ductility were analyzed in the grinding of SiC ceramics. The results showed that the spiral and straight-line mode vibration patterns were the main feature of the machined surface, and its continuity was mainly affected by the phase shift. Furthermore, for the in-phase shift condition, the grinding ductility was more significant than for the out-of-phase shift due to the continuously decreasing relative linear speed between the wheel and workpiece. Full article

(This article belongs to the Special Issue Processing Technology of Brittle Crystal Materials)

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12 pages, 4503 KiB

Open AccessArticle

Numerical and Experimental Investigation on the Abrasive Flow Machining of Artificial Knee Joint Surface

by Renquan Ji, Zijian Qi, Junchao Chen, Li Zhang, Kaifeng Lin, Shasha Lu and Yanbiao Li

Crystals 2023, 13(3), 430; https://doi.org/10.3390/cryst13030430 - 02 Mar 2023

Cited by 14 | Viewed by 1625

Abstract

The titanium alloy artificial knee joint is used extensively in the current medical industry due to its distinct characteristics and properties that are like the real human knee joint, but it does need to be polished to improve its performance and service life before it can be used. Due to the complicated surface profile, the traditional abrasive flow machining technique cannot achieve a good surface finish offering uniformity and quality. Thus, in this paper, a proper constrained flow channel is designed to conduct the abrasive flow machining of the titanium alloy artificial knee joint surface to overcome these issues. A numerical study is first conducted to explore the distribution of abrasive flow velocity and pressure near the target surface in the constrained flow channel by using the COMSOL Multiphysics software, and it is found from the distribution of the dimensionless material removal rate on the target surface that the exchange of the abrasive flow inlet and outlet during the machining process is recommended to improve the surface finish uniformity. Then, the corresponding experiments are conducted to analyze the surface morphology before and after the abrasive flow machining process. It is found that the surface roughness of the target surface decreases from approximately 394 nm to 171 nm with good uniformity as well. Therefore, the proposed abrasive flow machining method with a properly designed constrained flow channel is useful for the rough polishing and fine finishing of the titanium alloy artificial joint. Full article

(This article belongs to the Special Issue Processing Technology of Brittle Crystal Materials)

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18 pages, 11256 KiB

Open AccessArticle

Ultraviolet Nanosecond Laser-Ablated Groove Analysis of 2.5D C_f/SiC Composites

by Tangyong Zhang, Fei Liu, Yao Liu, Chongjun Wu and Steven Y. Liang

Crystals 2023, 13(2), 223; https://doi.org/10.3390/cryst13020223 - 25 Jan 2023

Cited by 2 | Viewed by 1510

Abstract

The 2.5D C_f/SiC composite is a typical heterogeneous material with the characteristics of anisotropy, which makes it difficult to predict the size and damage removed by the traditional contact removal process. This paper adopted the ultraviolet nanosecond laser to ablate the C_f/SiC composites by considering the heterogeneous structure’s effect. The ablated groove topography and size prediction are effective in revealing the machined quality with predictable groove sizes. The effects of laser processing parameters on the groove morphology and surface thermally affected zone are investigated with the thermal removal mechanism. A regression model is established by considering the scanning times, scanning speed, laser power and pulse width as the main variables. In the regression models, the relative error values are all below 10%. It is revealed that the groove width diminishes with the scanning speed and increases as the laser power increases. However, the influence of the scanning times and pulse width is small, and the overall variation range is within ±10 μm. The results show that the arrangement direction of carbon fibers has an impact on laser processing, especially when the pulse width is 0.25 μs, upon which the opposite change occurs. Carbon fiber grooves are not obvious and are barely observed in the laser processing of the parallel carbon fiber direction, and the grooves are slightly uneven. This study could be helpful in analyzing the grooves of C_f/SiC affected by the laser processing process, which could support the hybrid machining of the C_f/SiC composites. Full article

(This article belongs to the Special Issue Processing Technology of Brittle Crystal Materials)

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20 pages, 5021 KiB

Open AccessArticle

Study on Grinding Force of Two-Dimensional Ultrasonic Vibration Grinding 2.5D-C/SiC Composite Material

by Yunguang Zhou, Chuanchuan Tian, Shiqi Jia, Lianjie Ma, Guoqiang Yin and Yadong Gong

Crystals 2023, 13(1), 151; https://doi.org/10.3390/cryst13010151 - 15 Jan 2023

Cited by 8 | Viewed by 1807

Abstract

The grinding force is an important index during the grinding process, which affects the surface quality and other aspects after machining. However, the research on the grinding force of ceramic matrix composites assisted by two-dimensional ultrasonic vibration-assisted grinding is very weak. In this paper, the impact of the relationship between the critical cutting depth and the maximum undeformed chip thickness on the removal mode of ceramic matrix composites was analyzed. On this basis, the grinding force model of two-dimensional ultrasonic vibration-assisted grinding were developed for ductile removal and brittle removal, respectively. Finally, the correctness of the model was verified, and the impact of grinding parameters on the grinding force was analyzed. The experimental results show that compared with the conventional grinding force, the two-dimensional ultrasonic vibration assisted grinding force decreases obviously. When the feed rate and grinding depth increase, the grinding force increases. When the grinding velocity and ultrasonic amplitude increase, the grinding force decreases. Compared with the experimental value, the average relative error of normal grinding force is 8.49%, and the average relative error of tangential grinding force is 13.59%. The experimental and theoretical values of the grinding force have a good fitting relationship. Full article

(This article belongs to the Special Issue Processing Technology of Brittle Crystal Materials)

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19 pages, 11035 KiB

Open AccessArticle

Machining Performance Analysis of Rotary Ultrasonic-Assisted Drilling of SiC_f/SiC Composites

by Jingyuan He, Honghua Su, Ning Qian and Pengfei Xu

Crystals 2022, 12(11), 1658; https://doi.org/10.3390/cryst12111658 - 17 Nov 2022

Cited by 3 | Viewed by 1751

Abstract

An SiC_f/SiC composite has the following excellent properties: high strength, low specific gravity, and high temperature resistance, which has great prospects in the combustion chamber of rockets or aero engines. Hole-making in SiC_f/SiC parts is an important processing method. Generally, water-based or oil-based coolants are avoided, so dry drilling is the primary hole-making approach for SiC_f/SiC. However, the abrasion resistance and high hardness of SiC_f/SiC often lead to fast tool wear as well as serious damage to the fiber and matrix during dry drilling. This study proposes an innovative strategy for hole-making in SiC_f/SiC parts—rotary ultrasonic-assisted drilling (RUAD) using an orderly arranged brazed diamond core drill. The influence of tool life and wear on drilling accuracy is analyzed. Additionally, the impacts of the process parameters of conventional drilling (CD) and RUAD on drilling force, torque, the surface roughness of the hole wall, and the exit tearing factor are investigated. The results show that the orderly arranged brazed diamond core drill exhibits longer tool life and higher accuracy in hole-making. Meanwhile, compared with CD, RUAD with the proposed core drill effectively improves the drilling quality and efficiency, and reduces the force and torque of drilling. The range of process parameters for dry drilling is broadened. Full article

(This article belongs to the Special Issue Processing Technology of Brittle Crystal Materials)

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18 pages, 6397 KiB

Open AccessArticle

Determination of Heat Transfer Coefficient by Inverse Analyzing for Selective Laser Melting (SLM) of AlSi10Mg

by Chongjun Wu, Weichun Xu, Shanshan Wan, Chao Luo, Zhijian Lin and Xiaohui Jiang

Crystals 2022, 12(9), 1309; https://doi.org/10.3390/cryst12091309 - 16 Sep 2022

Cited by 3 | Viewed by 1930

Abstract

Heat treatment can improve performance and control quality in the additive manufacturing process. In the numerical simulation of heat treatment, the accuracy of the heat transfer coefficient will have a significant impact on the accuracy of the simulated temperature field. At present, The inverse analysis method is the most common and effective method to determine the heat transfer coefficient. Taking the actual temperature curve as the input condition, the heat transfer coefficient values of the heating, quenching, and air cooling components in the heat treatment process are successfully obtained. Based on the obtained heat transfer coefficient, a mathematical model of the heat transfer coefficient change with temperature during heat treatment is established. The heat transfer coefficient obtained by the inverse analysis method is then applied to the simulation of heat treatment, and more accurate simulation results are obtained. It is proven in this work that the inverse analysis method can improve the accuracy of the simulation model in the heat treatment process of AlSi10Mg. Full article

(This article belongs to the Special Issue Processing Technology of Brittle Crystal Materials)

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8 pages, 32358 KiB

Open AccessArticle

Surface Morphology Evaluation and Material Removal Mechanism Analysis by Single Abrasive Scratching of RB-SiC Ceramics

by Zhangping You, Haiyang Yuan, Xiaoping Ye and Liwu Shi

Crystals 2022, 12(7), 879; https://doi.org/10.3390/cryst12070879 - 21 Jun 2022

Viewed by 1390

Abstract

Reaction-Bonded Silicon Carbide (RB-SiC) ceramics possessing excellent mechanical and chemical properties, whose surface integrities have an essential effect on their performance and service life, have been widely used as substrates in the core parts of aerospace, optics and semiconductors industries. The single abrasive scratching test is considered as the effective way to provide the fundamental material removal mechanisms in the abrasive lapping and polishing of RB-SiC ceramics for the best surface finish. In this study, a novel single abrasive scratching test with an increasing scratching depth has been properly designed to represent the real abrasive lapping and polishing process and employed to experimentally investigate the surface integrity regarding different scratching speeds. Three typical and different material removal stages, including the ductile mode, ductile–brittle transition mode and brittle mode, can be clearly distinguished and it is found that in the ductile material removal stage by increasing the scratching speed would inhibit the plastic deformation and improve its surface integrity. It is also found that in the ductile–brittle transition and brittle material removal stages, to increase the scratching speed would inhibit the plastic deformation due to the fast scratching speed that limits the time of plastic deformation on the target, but it also results in the increased length of lateral cracks with the increased scratching speed which can reflect that the size of brittle chips, like brittle fractures and large grain fragmentations, increases as the scratching speed increases. It can provide the references for the optimization of the abrasive lapping and polishing of RB-SiC ceramics with high efficiency and surface quality. Full article

(This article belongs to the Special Issue Processing Technology of Brittle Crystal Materials)

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18 pages, 13746 KiB

Open AccessArticle

Splitting Opaque, Brittle Materials with Dual-Sided Thermal Stress Using Thermal-Controlled Fracture Method by Microwave

by Xiaoliang Cheng, Zongyang He, Hailong Wang and Yang Wang

Crystals 2022, 12(6), 801; https://doi.org/10.3390/cryst12060801 - 06 Jun 2022

Viewed by 1446

Abstract

The thermal-controlled fracture method has been increasingly focused upon in the high-quality splitting of advanced brittle materials due to its excellent characteristics related to the fact that it does not remove material. For opaque, brittle materials, their poor fracture quality and low machining capacity resulting from their single-sided heat mode is a bottleneck problem at present. This work proposed the use of dual-sided thermal stress induced by microwave to split opaque, brittle materials. The experimental results indicate that the machining capacity of this method is more than twice that of the single-sided heat mode, and the fracture quality in splitting opaque, brittle materials was significantly improved by dual-sided thermal stress. A microwave cutting experiment was carried out to investigate the distribution characteristic of fracture quality by using different workpiece thicknesses and processing parameters. A dual-sided thermal stress cutting model was established to calculate the temperature field and thermal stress field and was used to simulate the crack propagation behaviors. The accuracy of the simulation model was verified using temperature measurement experiments. The improvement mechanism of the machining capacity and fracture quality of this method was revealed using the fracture mechanics theory based on calculation results from a simulation. This study provides an innovative and feasible method for cutting opaque, brittle materials with promising fracture quality and machining capacity for industrial application. Full article

(This article belongs to the Special Issue Processing Technology of Brittle Crystal Materials)

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16 pages, 7322 KiB

Open AccessArticle

Surface Shape Evolution of Optical Elements during Continuous Polishing of Fused Quartz

by Yiren Wang, Feihu Zhang and Chen Li

Crystals 2022, 12(5), 736; https://doi.org/10.3390/cryst12050736 - 20 May 2022

Cited by 3 | Viewed by 1770

Abstract

Continuous polishing is the first choice for machining optical elements with a large aperture. The lubrication in the continuous polishing is an important factor affecting the surface quality of the optical elements. In this study, the lubrication system between the optic element and polishing lap was analyzed firstly and then was verified by the measurement experiment of the friction coefficient. In addition, the numerical simulation model of the mixture lubrication was established. The polishing pressure distribution and material removal distribution can be obtained by the model. The influences of the rotating speed, optical element load, and surface roughness of the polishing lap on polishing pressure were also analyzed. Finally, the influence rules of the lubrication on the surface shape of optical elements were revealed by the polishing experiments. Full article

(This article belongs to the Special Issue Processing Technology of Brittle Crystal Materials)

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18 pages, 7078 KiB

Open AccessArticle

Surface Quality Experimental Study on Rotary Ultrasonic Machining of Honeycomb Composites with a Circular Knife Cutting Tool

by Gang Liu, Jie Yang, Liqiang Zhang, Qiuge Gao, Long Qian and Rongyao Zhang

Crystals 2022, 12(5), 725; https://doi.org/10.3390/cryst12050725 - 19 May 2022

Cited by 4 | Viewed by 1732

Abstract

Honeycomb composites (HCs) are diversely employed in aerospace, national defense and other fields owing to their remarkable spatial geometry and excellent mechanical properties. Their complex hexagonal cell structure and heterogeneous material properties cause major problems when implementing high-quality processing. Surface defects generated by processing will reduce the capability and service lifespan of the honeycomb sandwich structure. Therefore, the high quality of HCs is a topic of close attention for researchers. In this paper, the consequences of different cutting parameters of rotary ultrasonic machining (RUM) on surface quality with an ultrasonic circular knife (UCK) were studied through multiple groups of single-factor and orthogonal experiments with two-factors/four-levels and one-factor/three-levels. The single factor experiment was used to explain the effect that the degree of cutting parameters has on surface quality, and the orthogonal experiments were applied to explain the interaction between the processing parameters and the influence law of each factor on surface quality. Therefore, the reasonable cutting parameters of HCs were determined through experimental results to provide guidance for the realization of the precise and efficient machining of HCs. This study can provide a basis for the subsequent comprehensive consideration of various factors to achieve high-quality machining of HCs. Full article

(This article belongs to the Special Issue Processing Technology of Brittle Crystal Materials)

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Review

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13 pages, 2232 KiB

Open AccessReview

Review on Research and Development of Abrasive Scratching of Hard Brittle Materials and Its Underlying Mechanisms

by Huina Qian, Mengkai Chen, Zijian Qi, Qi Teng, Huan Qi, Li Zhang and Xiaohang Shan

Crystals 2023, 13(3), 428; https://doi.org/10.3390/cryst13030428 - 02 Mar 2023

Cited by 11 | Viewed by 2770

Abstract

Hard brittle materials such as ceramics and crystals are commonly utilized in various industries, including information technology, mechanical engineering, and semiconductors. These materials, known for their high brittleness and hardness but low fracture toughness, pose challenges in efficient and high-quality machining. Current abrasive machining techniques involve rough grinding, fine grinding, and polishing processes, with the latter being the most time-consuming and accounting for over half of the total machining time. Improving processing parameters in rough and fine grinding can increase machining efficiency, reduce surface and subsurface damage, and improve workpiece quality, ultimately reducing the polishing time. This paper explores the abrasive scratching of hard brittle materials, examining the nucleation and propagation of cracks causing surface and subsurface damage, and the underlying mechanisms. The research provides suggestions for enhancing abrasive machining efficiency and ensuring the surface quality of hard brittle materials. Full article

(This article belongs to the Special Issue Processing Technology of Brittle Crystal Materials)

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