Self-lubricating Ceramic Tool Research Articles

Synergetic lubrication between self-lubricating ceramic tools and nanofluids: Advancing the application of self-lubricating ceramic cutting tools

In the field of ceramic tool processing, the incorporation of solid lubricants into self-lubricating ceramic tools forms a supportive lubricating film during the cutting process, effectively enhancing the cutting performance of the tools. Concurrently, Nanofluid Minimum Lubrication Technology (NMQL), as an emerging lubrication method, holds the potential to improve tool performance. However, due to significant cutting forces, NMQL faces challenges in effectively reaching the machining area, thereby limiting its cooling and lubricating efficiency. To overcome this challenge, our study proposes an innovative strategy by combining self-lubricating ceramic tools with nanofluids, aiming to enhance ceramic tool performance through synergistic lubrication effects. We conducted experimental studies under various lubrication conditions, comparing the performance of self-lubricating ceramic tools with traditional ceramic tools in cutting operations. A comprehensive evaluation of parameters such as tool life, cutting temperature, and cutting forces was performed. The results demonstrate that self-lubricating ceramic tools enable more efficient penetration of nanofluids into the machining area. In comparison to sole nanofluid lubrication, the synergistic effect significantly improves tool performance while substantially reducing production costs. This research contributes to advancing the development and widespread application of self-lubricating ceramic tools in the field of mechanical processing.

A critical review on functionally graded ceramic materials for cutting tools: Current trends and future prospects

Abstract This review is an attempt to explore the challenges that need to be addressed to fully utilize the potential of ceramic-based functionally graded cutting tools (FGCTs). The various aspects covered in the review include the most recent experimental and numerical work related to FGCTs, the current research trends and the need for these tools, the identification of potential material combinations, synthesis techniques and their limitations, and finally a presentation of the most recent work. To find general tribological performance, various wear mechanisms involved in the cutting process are explored. Some recent experimental and numerical works related to the self-lubricating phase in functionally graded structure and the need for self-lubricating ceramic tools, identifying potential high-temperature solid lubricants, and their limitations are also discussed. More recent and dominating fabrication methods are also discussed in detail along with a brief review of some promising methods. The implementation of numerical modeling and computational frameworks validated through experiments is found to lead to the design and development of cost-effective and efficient FGCTs. Finally, some research gaps are identified and future directions for innovative FGCT materials are proposed.

Effect of CaF2@SiO2 on Si3N4/TiC Composite Ceramic Materials: Molecular Dynamics Analysis and Material Preparation

Molecular dynamics simulations allow to investigate the microscopic evolution of a structure, and can also point the way to tool material design. In this paper, the effect of adding CaF2 and CaF2@SiO2 on the Si3N4/TiC system is studied using molecular dynamics simulations. The results show that the system with the addition of CaF2@SiO2 to the model has a higher hardness than the system with the addition of CaF2. In order to obtain the optimum parameters for self-lubricating ceramic tools, the effect of adding different amounts of CaF2@SiO2 on the Si3N4/TiC system was investigated. The Si3N4/TiC/CaF2@SiO2 system achieved optimum mechanical properties when four CaF2@SiO2 were included in the model. By analyzing the effect of the sintering temperature on the system, it was deduced that the hardness achieved a maximum value of 15.89 GPa and the modulus of elasticity reached 132.53 GPa when the sintering temperature was at 2073 K. Based on this sintering parameter, the Si3N4/TiC/CaF2@SiO2 composite ceramic tool material was experimentally prepared with the mechanical properties of 15.66 GPa hardness and 128.08 GPa modulus of elasticity. The experimental results were consistent with the simulation results.

Cutting performance and antifriction mechanism of Al2O3/TiC/TiB2/h-BN@Al2O3 self-lubricating ceramic tool

The machinability and wear reduction mechanism of self-repairing and self-lubricating ceramic tools sintered by vacuum hot-pressing method in the dry turning of 40Cr hardened steel was studied. By comparing the cutting performance and wear morphology of AT (Al2O3/TiC) ceramic tools under different cutting parameters, it was found that AT10B@5 (Al2O3/TiC/10 vol% TiB2/5 vol% h-BN@Al2O3) tool has a longer service life and better machining quality. Owing to the precipitation of solid lubricant during the cutting of AT10B@5 ceramic tool, the friction force during the cutting is reduced, thus decreasing the cutting force and cutting temperature of AT10B@5 ceramic tool during the cutting. The main cutting force decreased by 20.8%; the cutting temperature decreased by 22.2%; and the friction coefficient of front tool face decreased by 11.6% compared with AT tool. This effectively improved the surface quality of working parts, reduced the tool wear, increased the processing quality of work piece, and prolonged the tool life.

Self-lubricating ceramic tool materials synergistically toughened by nano-coated particles and silicon carbide whiskers

Nano-coated particles and whiskers were used as reinforcing additives for ceramic tool materials to take advantage of synergistic toughening and enhancement mechanisms. An Al2O3/TiC/CaF2@SiO2/SiCw ceramic tool material was fabricated by hot-pressing. Self-lubricating ceramic tool materials toughened by nano CaF2@SiO2 coated particles and SiC whiskers were studied. When the addition content of nano CaF2@SiO2 coated particles was 10 vol% and the content of SiC whiskers was 20 vol%, ceramic tool materials with the best comprehensive properties were obtained. The results showed that the hardness of the ceramic tool material was 16.52 GPa, the flexural strength was 698 MPa, and the fracture toughness was 6.89 MPa m1/2. Compared with the ceramic tool material with 10 vol% nano CaF2 particles and 20 vol% SiC whiskers, the above properties were improved by 7.06%, 31.74% and 19.06%, respectively. The SiC whiskers played a toughening role, while nano CaF2@SiO2 coated particles reduced the porosity, the compactness and also filled between the grain boundaries of the ceramic tool materials during sintering. This improved the interfacial bonding between ceramic grains, which increased the incidence of transgranular fracture in the ceramic tool materials.

Mechanical properties, microstructure and crack healing ability of Al2O3/TiC/TiB2/h-BN@Al2O3 self-lubricating ceramic tool material

To prepare a self-lubricating ceramic tool with excellent mechanical properties and crack healing ability, the h-BN@Al2O3 solid lubricant with a core-shell structure was prepared by the heterogeneous nucleation method, and was added into Al2O3/TiC ceramic matrix together with TiB2. Examination of the micro-morphology and phase composition of h-BN@Al2O3 found that the surface of the solid lubricant h-BN was coated with Al(OH)3 at first, and after calcination at 1200 °C, a dense and uniform Al2O3 shell was formed. At the same time, the effects of the h-BN@Al2O3 addition on the ceramic tool material were studied. The mechanical properties of the ceramic tool material with h-BN@Al2O3 were improved relative to than those with h-BN. The optimal content of h-BN@Al2O3 solid lubricant was 5 vol%. In the friction and wear test, h-BN in h-BN@Al2O3 particles can be stripped to form a solid lubricating film on the material surface, which plays a good role in reducing wear and resisting wear. The crack healing ability of the self-lubricating ceramic tool material was studied by prefabricating cracks with a length of 400 μm on the surface. After a heat treatment at 700 °C for 60 min, the surface cracks of the ceramic tool material were completely healed, and the flexural strength was restored to 90% of that of the smooth samples. The oxidation of TiB2 and h-BN in ceramic tool materials is the main reason for crack healing.

Cutting Behavior of Self-Lubricating Ceramic Tool in Dry Machining of 40Cr Quenched Steel

In this paper, the dry cutting performance of Al2O3/TiC-based ceramic composites with nanoCaF2 was studied. Compared with the Al2O3/TiC ceramic tool, the Al2O3/TiC/CaF2 ceramic tool has lower cutting force, cutting temperature and surface roughness when milling 40Cr hardened steel. Three cutting parameters of cutting speed, feed per tooth, and cutting depth were used to conduct orthogonal experiments to study its changing trend. Through testing of cutting force, cutting temperature and surface roughness, and by comparison with ceramic tools without nanosolid lubricant added, the order of influence of three cutting parameters on cutting force, cutting temperature and surface roughness was obtained. The experimental results showed that the cutting force, cutting temperature and surface roughness of Al2O3/TiC/CaF2 ceramic tools containing nanoCaF2 werebetter than those of Al2O3/TiC ceramic tools. The cutting force, the cutting temperature, and the surface roughness were respectively reduced by 16.5%, 25.8% and 43% compared to when no solid lubricant was added. In addition, after adding solid lubricant, the effect of cutting depth on cutting force was significantly reduced. The average friction coefficient of the tool rake surface was 31.1% lower than that of ceramic tools without solid lubricant. In order to explain this phenomenon, through scanning electron microscopy (SEM) scanning and energy spectroscopy (EDS) elemental analysis, the wear reduction mechanism of solid lubricants was analyzed, that is, during the cutting process, nanosolid lubricants precipitated and formed lubricating film on the rake surface of the tool to reduce the friction coefficient. This was also the main reason for reducing the cutting temperature.

Influence of CaF2@Al2O3 on Cutting Performance and Wear Mechanism of Al2O3/Ti(C,N)/CaF2@Al2O3 Self-Lubricating Ceramic Tools in Turning.

This study aimed at improving the cutting performance of a ceramic tool to which were added solid lubricant particles. We prepared the self-lubricating ceramic tool by adding CaF2@Al2O3 instead of CaF2, and the self-lubricating ceramic tool with Al2O3 as matrix phase, Ti(C,N) as reinforcement phase. The properties of the ceramic tool with different contents of CaF2@Al2O3 and CaF2 were studied by turning 40Cr. Compared with the ceramic tool with 10 vol.% CaF2, the main cutting force and the cutting temperature of the ceramic tool with 10 vol.% CaF2@Al2O3 decreased by 67.25% and 38.14% respectively. The wear resistance and machining surface quality of the ceramic tool with CaF2@Al2O3 were better than the ceramic tool to which were directly added CaF2. The optimal content of CaF2@Al2O3 particles was determined to be 10 vol.%. The addition of CaF2@Al2O3 particles effectively reduces the adverse effect of direct addition of CaF2 particles on the ceramic tool, and plays a role in improving the cutting performance of the ceramic tool.

Preparation of nano - coating powder CaF2@Al(OH)3 and its application in Al2O3/Ti(C,N) self-lubricating ceramic tool materials

Nano CaF2 particles of different sizes were prepared by direct precipitation. The diameters of nano CaF2 particles prepared in mixed solvent can reach 5–7 nm, and can be effectively dispersed. The surface of nano CaF2 was modified and coated by heterogeneous nucleation method. A shell layer of Al(OH)3 was coated on the surface of nano CaF2, and the structure and coating mechanism of the coated powder were analyzed. Under varying preparation conditions, the surface morphology of CaF2@Al(OH)3 was analyzed using TEM and SEM. The results showed that the coating powder showed good dispersion in mixed solvents, and the particle size of the composite powder was about 20 nm. Self-lubricating ceramic tool materials were prepared by adding coating particles to the Al2O3/Ti(C,N) matrix. The coating powder shell and the matrix material melt during sintering, so that CaF2 forms nanostructures in the particles. thereby improving the mechanical properties of the material. Cutting experiments show that the addition of coating particles can effectively reduce the temperature, cutting force and friction coefficient in the cutting process of the tool, thus improving the cutting performance of the tool material.

Preparation of Al2O3/Ti(C,N)/ZrO2/CaF2@Al(OH)3 Ceramic Tools and Cutting Performance in Turning.

Aiming at the contradiction between the lubricating performance and mechanical performance of self-lubricating ceramic tools. CaF2@Al(OH)3 particles were prepared by the heterogeneous nucleation method. An Al2O3/Ti(C,N) ceramic tool with CaF2@Al2(OH)3 particles and ZrO2 whiskers was prepared by hot press sintering (frittage). The cutting performances and wear mechanisms of this ceramic tool were investigated. Compared with the Al2O3/Ti(C,N) ceramic tool, the Al2O3/Ti(C,N)/ZrO2/CaF2@Al(OH)3 ceramic tool had lower cutting temperatures and surface roughness. When the cutting speed was increased from 100 m/min to 300 m/min, a lot of CaF2 was smeared onto the surface of the ceramic tool, and the flank wear of the Al2O3/Ti(C,N)/ZrO2/CaF2@Al(OH)3 ceramic tool was reduced. The main wear mechanisms of the Al2O3/Ti(C,N)/ZrO2/CaF2@Al(OH)3 ceramic tool were adhesive wear and micro-chipping. The formation of solid lubricating film and the improvement of fracture toughness by adding ZrO2 whiskers and CaF2@Al(OH)3 were important factors for the Al2O3/Ti(C,N)/ZrO2/CaF2@Al(OH)3 ceramic tool to have better cutting performances.

Synthesis and Simulation of CaF2@Al(OH)3 Core-Shell Coated Solid Lubricant Composite Powder

In self-lubricating ceramic tools, adding CaF2 will significantly reduce the mechanical properties of ceramic tools. Based on heterogeneous nucleation theory, we have recently prepared aluminum hydroxide (Al(OH)3) coating on calcium fluoride (CaF2) through a liquid-phase heterogeneous nucleation method. By adding CaF2@Al(OH)3 coated powder to replace CaF2 powder, the self-lubricating ceramic tools maintain higher lubricity while also having better mechanical properties. The coating process was further confirmed by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, we used the molecular simulation software to simulate the suspension system of CaF2, Al(NO3)3·9H2O, and Al(OH)3 to study the process of Al(OH)3 coating on the surface of CaF2 particle to form CaF2@Al(OH)3 powders with core-shell structure. Further, the formation and evolution of Al(OH)3 molecules on the surface of CaF2 were analyzed.

Synthesis of CaF2 Nanoparticles Coated by SiO2 for Improved Al2O3/TiC Self-Lubricating Ceramic Composites.

In order to reduce the influence of CaF2 addition on the mechanical properties of self-lubricating ceramic tools, we applied a silicon dioxide (SiO2) coating on calcium fluoride (CaF2) nanoparticles through hydrolysis and condensation reactions using the tetraethoxysilane (TEOS) method. The powder was dried by the azeotropic method, so that it acquired a better dispersibility. The resulting composite powders were characterized using XRD (X-ray diffraction) and TEM (transmission electron microscopy), showing that the surface of CaF2 was coated with a layer of uniform and compact SiO2. SiO2 shells with different thicknesses could be obtained by changing the amount of TEOS added, and the thickness of the SiO2 shells could be controlled between 1.5 and 15 nm. At the same time, a ceramic material containing CaF2 nanoparticles and CaF2@SiO2-coated nanoparticles was prepared. It had the best mechanical properties when CaF2@SiO2-coated nanoparticles were added; its flexural strength, fracture toughness, and hardness were 562 ± 28 MPa, 5.51 ± 0.26 MPa·m1/2, and 15.26 ± 0.16 GPa, respectively. Compared with the ceramic tool containing CaF2 nanoparticles, these mechanical properties were increased by 17.57%, 12.67%, and 4.88%, respectively. The addition of CaF2@SiO2-coated nanoparticles greatly improved the antifriction and wear resistance of the ceramic material, and the antifriction and wear resistance were balanced.

Investigation of Al2O3/TiB2 ceramic cutting tool materials with the addition of core–shell structured Ni–B coated CaF2

AbstractAl2O3 based self-lubricating ceramic tool materials with the addition of CaF2@Ni–B were prepared using the vacuum hot-pressing technique. The microstructure, mechanical properties and cutting performance of the material with different contents of CaF2@Ni–B were studied. Compared to its counterpart tool material without CaF2@Ni–B, the fracture toughness and flexural strength of the Al2O3/TiB2/(CaF2@Ni–B) self-lubricating ceramic tool materials increased by 40.5 % and 10.1 %, and the tool life increased by 25 %.

Mechanical properties and microstructure of Al2O3/Ti(C,N)/CaF2@Al2O3 self-lubricating ceramic tool

Due to the poor mechanical properties of solid lubricants, direct addition to the ceramic matrix will reduce the mechanical properties of the material. In this study, Al(OH)3 was coated on the surface of nano CaF2 by non-uniform nucleation method and added to Al2O3/Ti(C,N) ceramic matrix. Al2O3/Ti(C,N)/CaF2@Al2O3 was prepared by vacuum hot pressing sintering. Compared with the material directly added with nano-solid lubricant, the mechanical properties of ceramic tools added with coated nano-solid lubricant have been significantly improved. Among them, when the content of coated nano-solid lubricant is 10 vol%, the ceramic material has better comprehensive mechanical properties. SEM observation shows that the cross-sectional particle distribution of nano-coated powder ceramic material is relatively uniform and has good compactness. The fracture mode of ceramic materials is a mixed fracture mode of intergranular fracture and transgranular fracture.

Influence of CaF2@Al2O3 on the friction and wear properties of Al2O3/Ti(C,N)/CaF2@Al2O3 self-lubricating ceramic tool

Abstract The Al2O3/Ti(C,N)/CaF2@Al2O3 self-lubricating ceramic tool materials with different CaF2@Al2O3 content were designed. The influence of CaF2@Al2O3 on the friction and wear properties of Al2O3/Ti(C,N)/CaF2@Al2O3 self-lubricating ceramic tool materials were studied. The results show that CaF2 as the core in Al2O3/Ti(C,N)/CaF2@Al2O3 self-lubricating ceramic tool material make the tool material have good lubricating ability, and Al2O3 as the shell will improve the wear resistance of the tool material. The friction coefficient of the Al2O3/Ti(C,N)/CaF2@Al2O3 self-lubricating ceramic tool materials with 10 vol% of CaF2@Al2O3 was 0.301, which was 90% lower than that of the tool material without CaF2@Al2O3. With the increasing of CaF2@Al2O3 content, the friction coefficient decreased, but the wear rate decreased at first and then increased a certain period later.

Mechanical properties and microstructure of Al2O3/TiC based self-lubricating ceramic tool with CaF2@Al (HO)3

The CaF2@Al2O3 coated powder with shell-core structure was prepared by liquid-phase non-uniform nucleation method. Based on the successful preparation of Al(OH)3 coated CaF2 powder, Al2O3/TiC self-lubricating tool was prepared by wet dispersion mixing and vacuum hot pressing sintering process. The microstructure and performance of the self-lubricating ceramic tool with different volume content of CaF2@Al(OH)3 coated powders were investigated. The results show that when the CaF2@Al2O3 content is 10 vol%, the comprehensive mechanical properties of Al2O3/TiC/CaF2@Al2O3 tool materials is the best, the hardness is 16.86 GPa, the flexural strength is 662 MPa, and the fracture toughness is 6.34 MPa·m1/2. Compared with the traditional Al2O3/TiC/10 vol%CaF2 self-lubricating ceramic cutting tools, Al2O3/TiC/10 vol% CaF2@Al2O3 ceramics in flexural strength, fracture toughness and hardness were increased 19.06%, 36.9%, 12.25%, of which the most obvious increase in fracture toughness.

Fabrication techniques and cutting performance of micro-textured self-lubricating ceramic cutting tools by in-situ forming of Al2O3-TiC

In this study, different geometric micro-textured ceramic tools (MST-0, MST-1, MST-2) are designed using the software AdvantEdge (AE). The designed tools are used to perform FEM (finite element modelling) simulation of the cutting process. The simulation results show that, compared with the traditional non-texture tool (MST-0), applying the appropriate shape and size of micro-texture to ceramic cutting tools can significantly reduce the cutting force, decrease the cutting temperature and improve the cutting performance of the tool. Additionally, an experimental study was conducted that involved the fabrication of hot-pressing sintered micro-textured self-lubricating ceramic tools (MST-1, MST-2) by means of in-situ forming method. Furthermore, cutting tests to compare the cutting performance of the micro-textured self-lubricating ceramic tools with the traditional non-textured tool (MST-0) were performed. The results indicate that the in-situ formed micro-textured ceramic cutting tools can effectively reduce the cutting force, the cutting temperature, and the rake face wear. During the cutting process, the abrasive grain of graphite that is placed into the micro-texture by in-situ forming is squeezed into the microstructure. Thus, the graphite overflows from the microstructure under abrasive grains and covers the rake face. This helps to reduce the friction between the chip and the rake face, which further reduces the cutting force and temperature, and improves the cutting performance of the tools. The texture pattern orientation of the micro-texture also affects the cutting performance of the tool. It is found that the best cutting performance is obtained by the transverse micro-texture tool.

Preparation of Al<sub>2</sub>O<sub>3</sub> Based Nano-Micro Composite Gradient Self-Lubricating Ceramic Tool Materials

Aiming at the low mechanical property of existing self-lubricating ceramic cutting tool material, a new Al2O3 based nanomicro composite gradient self-lubricating ceramic tool material was developed by applying the design concept of nanomicro composite. The self-lubricating ceramics was composed of ceramic matrix and self-lubricating component, and was prepared by hot pressing technology at a hot-pressing temperature of 1650°C, pressure of 30MPa, and duration of 15min. The model of gradient ceramic tool material is symmetrical composition distribution, and the compositional distribution n and layer number are 1.8 and 7, respectively. The result shows that the interfaces between layers are bonded well and no cracks or defects can be observed. Compare with the homogeneous material, the flexural strength, hardness and fracture toughness of Al2O3 based graded material increase by 74%, 5.2% and 3.9%, respectively.

Finite element design and fabrication of Al2O3/TiC/CaF2 gradient self-lubricating ceramic tool material

Based on the idea of a functionally gradient material, the gradient self-lubricating ceramic tools were designed to solve the problem that the antifriction property and wear resistance of self-lubricating ceramic tools cannot be simultaneously considered. Physical, composition distribution, and micromechanical models were established. The finite element method was used to analyze the residual thermal stress of symmetrically distributed gradient ceramic tools with different compositional distribution exponent (n) values. When n=1.8, the stress gradient was small and the lowest value of the maximum Von Mises stress was obtained. An Al2O3/TiC/CaF2 gradient self-lubricating ceramic tool material with good mechanical properties was then fabricated by hot-pressing technique according to the optimum design results. Residual stresses were calculated by indentation crack method. Results showed that in the gradient self-lubricating ceramic tool material, compressive stresses were formed in the surface layers, whereas tensile stresses were formed in the middle layer, which were consistent with FEM-calculated findings.

Cutting Performance of TiB<sub>2</sub>/WC/h-BN Micro/nano Composite Gradient Self-Lubricating Ceramic Tool when Machining Carbon Steel

Continuous cutting experiments of steel 45 were conducted to investigate cutting performance of TiB2/WC/h-BN micro/nano composite gradient self-lubricating ceramic tool. Influences of cutting speed on flank wear and tool life were analyzed. The results show that flank wear increases slightly when cutting speed V≥80 m/min, tool life increases initially and then decreases with increasing cutting speed. Wear mechanism was studied: the primary pattern of tool wear is abrasive wear and adhesive wear and solid-lubricants in tool have a noticeable wear-resistance effect during machining.