Si3N4陶瓷刀具在切削淬硬钢时的磨损行为

采用两种Ｓｉ２Ｎ４刀具在普通车床上对ＣｒＷＭｎ和４５钢进行切削试验，并用ＳＥＭ，ＥＤＡＸ，ＸＰＳ等方法对刀具的磨损进行分析。结果指出：试验的陶瓷刀具材料在切削不同淬硬钢时均存在最佳切削速度。在ＦＤ０１相比，ＦＤ０２陶瓷刀具有更佳的切削性能，最佳切削速度可提高７８％。在最佳速度以下切削，刀具侧面将发生粘着磨损；在最佳速度以上，则被加工材料产生微区熔化，导致材料大面积转移，发生剥层磨损，最佳速度以下切     

Injection molding of ceramic cutting tools for wood-based materials

In this study a mutable mold for ceramic cutting tools with inserts of different cutting angles and two different injection positions was designed. Three alumina-based ceramic feedstocks with different types and amount of second phases were developed. A mold filling study was carried out for both sprue positions in order to prove the molding behavior of the feedstock and the functionality of the mold. Debindering and sintering of molded green parts was arranged for each composition, respectively. Mechanical properties, microstructure and achieved cutting edge sharpness of produced tools were investigated. Results show that the mold design and injection molding process play a key role in order to manufacture cutting tools of best possible sharpness enabling a wood machining process. Feedstocks exhibit a good mold filling behavior resulting in comparatively sharp cutting edges of ≈10 μm after sintering. Mechanical properties show high potential for application of wood machining cutting tools.     

Cutting performance of microwave-sintered sub-crystal Al2O3/SiC ceramic tool in dry cutting of hardened steel

Tool life and failure mechanisms of a microwave-sintered sub-crystal Al₂O₃/SiC ceramic tool (AS) in dry turning hardened steel were studied. The AS tool with plane face shows better cutting performance and wear resistance than the commercial ceramic tool SW500 and cemented carbide tool YG8 at both low and high cutting speeds. It's suitable for dry cutting at high speed (210–270 m/min), the cutting distance is 5–8 times longer than that of other two tools. The results indicate that the ceramic tool fabricated by this pressureless sintering technology can satisfy the requirements of high-speed machining. Wear forms of AS tool at low cutting speed are slight crater wear and groove wear, which were mainly caused by abrasion. At high cutting speed, tool failure forms are cater wear, groove wear and slight chipping caused by severe abrasion and adhesion.     

Cutting performance and tool wear of SiAlON and TiC-whisker-reinforced Si3N4 ceramic tools in side milling Inconel 718

Cutting performance and tool wear of two ceramic tools, SiAlON and TiC-whisker-reinforced Si₃N₄, in the side milling processes of Inconel 718 are evaluated in comparison, including cutting force, temperature, surface morphology, tool wear and corresponding mechanism. Results show that these two ceramic tools has advantages and disadvantages respectively, due to the properties of ceramic matrixes and the evolutions of build-up edges. SiAlON ceramic tool has better resistance to wear, but causes poor surface quality. TiC-whisker-reinforced Si₃N₄ ceramic tool generates better surface quality, but bears severe wear. Brittle damage, as the main mode of wear, occurs to both ceramic tools in different formations. SiAlON ceramic tool is featured by crater-like damage on blades while TiC-whisker-reinforced Si₃N₄ ceramic tool is featured by whole-layer damage on flank faces.     

Self-lubricating behaviors of Al2O3/TiB2 ceramic tools in dry high-speed machining of hardened steel

In this paper, Al₂O₃/TiB₂ ceramic cutting tools with different TiB₂ content were produced by hot pressing. The fundamental properties of these ceramic cutting tools were examined. Dry high-speed machining tests were carried out on hardened steel. The tool wear, the cutting temperature, the cutting forces, and the friction coefficient between the tool and the chip were measured. It was shown that both the wear rates and the friction coefficient at the tool–chip interface of Al₂O₃/TiB₂ ceramic cutting tools in dry high-speed machining of hardened steel were reduced compared with that of in low-speed machining. The mechanisms responsible were determined to be the formation of a self-lubricating oxide film on the tool–chip interface owing to the tribological–chemical reaction by the elevated cutting temperature. The composition of the self-lubricating film was found to be the oxidation product of TiB₂ grains, which serves as lubricating additive on the wear track of the tool rake face. The appearance of this self-lubricating oxide film contributed to the improvement in wear resistance and the decrease of the friction coefficient. This action was even more effective with higher TiB₂ content. Cutting speed was found to have a profound effect on the self-lubricating behavior. In dry low-speed machining of hardened steel, the Al₂O₃/TiB₂ tools showed mainly adhesive and abrasive wear. While in dry high-speed machining, oxidation wear of the ceramic tools was the dominant mechanism due to the very high cutting temperature. No oxide film was formed on the tool–chip interface while machining in nitrogen atmosphere, and the tool wear resistance was correspondingly decreased.     

Cutting performance and wear mechanism of Sialon ceramic tools in high speed face milling GH4099

This work aims to reveal the cutting performance and wear mechanisms of Sialon ceramic tools for the high-speed face-milling of GH4099, with the goal of improving this process as well as designing more advanced ceramic cutting tools in the future. At the outset of this study, several single-factor experiments were designed with speed as a variable to gather various data on such tools. Failure patterns and tool life curves were first obtained through cutting tests. Afterwards, the tools were split at their place of wear (middle of notch and 1/2 depth of cut) to prepare for further analysis. Wear morphology and element composition distribution in the depth direction of the corresponding interface were then analyzed using a field emission scanning electron microscope (FE-SEM) and energy dispersive spectrometer (EDS) to explore potential diffusion and/or chemical wear. Finally, studies were conducted into the tools’ chemical wear under specific cutting conditions, finishing with a theoretical verification based on the thermodynamic principle of chemical reactions. This research discovered that notch wear was the main failure pattern for the high-speed face-milling of GH4099 under the suitable cutting conditions. Overall, the optimal cutting speed was 1000 m/min, with a tool life of about 3 min. Compared with cemented carbide tools, the machining efficiency for Sialon ceramic tools increased by over a factor of 16. The wear mechanisms for such tools demonstrated a mixture effect of abrasive, adhesive, diffusive and chemical wear. Diffusive wear mainly occurred in their flank faces, but did not constitute the main mechanism of notch wear; chemical wear proved to be a key reason for notch wear at higher temperatures. Based on the aforementioned research, this paper concludes with a proposed comprehensive model for notch wear.     

Performance and wear mechanism of spark plasma sintered WC-Based ultrafine cemented carbides tools in dry turning of Ti–6Al–4V

Cutting performance and failure mechanisms of spark plasma sintered (SPS) ultrafine cemented carbides in dry turning Ti–6Al–4V were studied. The tools of UYG8 (WC-8wt%Co) and UYG8V2B10 (WC-8wt%Co-0.2 wt%VC-1.0 wt%cBN) exhibited higher lifetime and better processing quality than the commercial YG8 cemented carbide tool. The cutting distance of UYG-8 and UYG8V2B10 tools are 1.8 and 1.6 times longer than that of YG8, respectively. Cutting-edge breakage was found as the main failure forms of the SPS cemented carbide tools containing low Co content (≤6 wt%), whereas the SPS cemented carbide tools containing high Co content (≥8 wt%) exhibited flank and rake wear as main failure forms caused by abrasion, adhesion, diffusion, and oxidation. UYG8V2B10 tool wear mechanism was affected by cutting speed and depth. Wear mechanisms of UYG8V2B10 tool are mainly adhesive wear and oxidative wear at low cutting speed, but follow adhesive wear and diffusive wear at higher cutting speed. Moreover, with increasing cutting depth, tool failure forms are mainly breakage and chipping, largely induced by high cutting temperature and severe cutting vibration.     

Cutting performance and wear mechanism of honeycomb ceramic tools in interrupted cutting of nickel-based superalloys

Nickel-based superalloys are favored because of high fatigue strength, corrosion resistance and oxidation resistance. However, the characteristics of high hardness, poor heat dissipation and sticking make the machinability of nickel-based superalloys poor, which is more serious for interrupted processing. Therefore, honeycomb ceramic tools are utilized to turn GH4169. Cutting and impact force, wear patterns and mechanism of honeycomb ceramic tools are analyzed. The results demonstrate that the impact force is greater than the average cutting force. Fractures, chipping and adhesion are the main wear characteristics of honeycomb ceramic tools. Furthermore, adhesive, abrasive and diffusion wear are the main wear mechanisms.     

Cutting performance improvement of Si3N4 ceramic cutting tools by adding boride

Cutting performances of silicon nitride (Si₃N₄) ceramic cutting tools with and without boride additive (2.5 vol% ZrB₂ or TiB₂) prepared by hot-pressing at 1500°C were investigated. Due to the α- to β-Si₃N₄ phase transformation and low densification temperature, boride-containing Si₃N₄ ceramics with high hardness and high toughness were obtained. The turning tests showed that the effective cutting lengths of the Si₃N₄–2.5 vol% TiB₂ ceramic (∼2480 m) and Si₃N₄–2.5 vol% ZrB₂ ceramic (∼2200 m) were higher than the monolithic Si₃N₄ ceramic (∼1780 m). As the toughness was improved while maintaining relative high hardness, the cutting performances of the boride-containing Si₃N₄-based inserts were improved by adding 2.5 vol% ZrB₂ or TiB₂. The improved cutting performance indicated that the boride-containing Si₃N₄ ceramics are expected to be used in the field of ceramic cutting tools.     

Alumina ceramic tool material with enhanced properties through the addition of bionic prepared nano SiC@graphene

Graphene-coated SiC nanoparticles containing graphene floating bands (SiC@G) were prepared by a liquid-phase laser irradiation technique, and SiC@G nanoparticles with high dispersivity were incorporated into an Al₂O₃ matrix. An Al₂O₃-based composite ceramic tool was prepared by spark plasma sintering (SPS), and the effects of SiC@G nanoparticles on the mechanical and cutting properties and microstructure of the materials were further investigated. Analysis of the cross-sectional morphology shows that SiC@G nanoparticles containing graphene floating bands were homogeneously dispersed in the composite, which resulted in tighter bonds between the Al₂O₃ particles. This particular core-shell structure increased the contact area between the graphene and the matrix due to the formation of a graphene 3D mesh by extrusion, which enhanced the difficulty of relative sliding of graphene. Second, this special core-shell structure also made the crack propagation path more tortuous, further increasing the energy consumed in the fracture process, which is conducive to improving the mechanical properties of ceramic tools. The addition of SiC@G nanoparticles improves the mechanical properties of Al₂O₃-based composite ceramic tools. The fracture toughness (7.2 Mpa·m^1/2) and flexural strength (709 MPa) increased by 75.6% and 28.7%, respectively. Cutting experiments with Al₂O₃/SiC/G composite ceramic tool and Al₂O₃/SiC@G composite ceramic tools on 40Cr hardened steel were performed. The results prove that the addition of SiC@G nanoparticles improves the cutting life by 18.1% and reduces the cutting force and friction coefficient by 6.3% and 14.8%, respectively.     

Experimental investigation of different morphology textured ceramic tools by in-situ formed for the dry cutting

Surface texture is considered an important measure to improve the cutting performance of a tool. In this study, we have prepared three types of textured and conventional tools on the rake face by an in-situ formed method. During the experiment, the best parameters of three types of textured tools were selected for dry cutting AISI 1045 steel at different cutting speeds. Cutting forces, cutting temperatures, workpiece surface roughness, and tool wear were measured during the cutting process. The results showed that textured tools have significantly reduced cutting force, cutting temperature, and tool wear, and the roughness of the workpiece was improved compared with the conventional tool. The micro-pit texture tool has less stress contact region than the micro-groove width texture tool, but the micro-groove width texture tool exhibiting the best cutting performance. This investigation clearly showed that the textured tool prepared by the in-situ formed method has improved cutting performance.     

The cutting performance of Al2O3 and Si3N4 ceramic cutting tools in the milling plywood

ABSTRACT

This research focuses on the cutting performance of Al₂O₃ and Si₃N₄ ceramic cutting tools in up-milling plywood, the results of which are as follows. First, whether the tool material is Al₂O₃ or Si₃N₄ ceramic, the cutting forces at low-speed cutting were less than those at high-speed cutting, and the machining quality at low-speed cutting was greater than that at high-speed cutting. Then, whether at low- or high-speed cutting, the cutting forces of Al₂O₃ cutting tools were higher than those of Si₃N₄ cutting tools, and the machining quality of plywood milled by Al₂O₃ ceramic cutting tools was poorer than that milled by Si₃N₄ ceramic cutting tools. Finally, Si₃N₄ ceramic cutting tools were more suitable to machine the wooden productions with much glue content than Al₂O₃ ceramic cutting tools for the better machined quality.     

两类陶瓷刀具的现状、性能与应用

综述了氧化铝系和氮化硅系两类陶瓷刀具的发展现状,阐述了两类陶瓷刀具的力学性能与切削性能,论述了两类陶瓷刀具的特点、加工范围以及合适的切削加工用量,提出了刀具使用过程中的一些注意问题。     

Investigation of novel multiscale textures for the enhancement of the cutting performance of Al2O3/TiC ceramic cutting tools

Currently, the high temperature and severe friction conditions at the tool-chip interface are the main reasons for ceramic tool wear failures. Surface texturing as a geometric extension for cutting tools is a promising way to extend their service life. In this study, a novel type of multiscale texture was developed, and its effect on the cutting performance of an Al₂O₃/TiC ceramic cutting tool while machining AISI H13 steel was explored in a conventional cooling environment. The cutting force, cutting temperature, and tool wear morphology were investigated at cutting velocities ranging from 80 to 249 m/min. Microgroove textured Al₂O₃/TiC ceramic tools were prepared for comparison. The results show that the structure of the multiscale textures maintained good integrity over the range of cutting velocities. Thus, the synergistic effect of the microscale and nanoscale textures promoted the introduction and permeation of the cutting fluid. Therefore, the multiscale textures effectively enhanced the cutting performance of the Al₂O₃/TiC ceramic tools.     

Cutting performance and wear mechanisms of the graphene-reinforced Al2O3-WC-TiC composite ceramic tool in turning hardened 40Cr steel

The Al₂O₃-WC-TiC-graphene composite ceramic tool (AWTG0.5) fabricated by two-step hot pressing was used to continuously turn the hardened 40Cr steel at different cutting speeds, and its cutting performance and wear mechanisms were compared with the homemade graphene-free AWTG0 ceramic tool and the commercial ceramic tools SG4 and LT55. The cutting performance of the AWTG0.5 tool was significantly better than that of the AWTG0, SG4 and LT55 tools. The contributions of graphene to the mechanical properties, lubricating properties and thermal conductivity of the AWTG0.5 tool were responsible for its higher cutting performance. The main wear mechanisms of the AWTG0.5 tool were adhesive wear and abrasive wear. In addition, it was also found that the anti-friction and wear resistance performances of the AWTG0.5 tool were superior to those of the other three tools. Its good anti-friction and wear resistance performances could be attributed to the formation of a self-lubricating layer induced by graphene pull-out.     

Optimized design of structural parameters of Si3N4-based ceramic tools with variable cross-section

Through theoretical analysis and finite element simulation experiments, this paper proposes an optimal design method for the structural parameters of ceramic tools with variable cross-sections. On this basis, the tool angles of Si₃N₄-based ceramic tools for cutting inconel 718 high-temperature alloy are investigated, including rake angle γ₀ = ?5°, clearance angle α₀ = 5°, cutting edge inclination λ_s = ?2°, cutting edge angle K_r = 45°. By comparing the main cutting force, temperature and chip-breaking effect of flat face and three different groove ceramic tools, it is found that straight chip breaker has the most obvious optimization effect, main cutting force is 14.5% lower than that of the flat face, the temperature is reduced by 10.2%, and radius of chip curl curvature is the smallest, which is easy to break chips.     

Longer‐lasting Al2O3‐SiCw‐TiC cutting tools obtained by spark plasma sintering

In this work, an electrically conductive powder mixture of alumina, silicon carbide whiskers, and titanium carbide has been used to obtain cutting tools with a standard SNGN geometry after machining spark plasma sintered disks with 150 mm in diameter and 10 mm height. The obtained cutting inserts from the sintered blanks were used in real conditions in order to make a wear study of this composition compared to the alumina‐silicon carbide whiskers inserts available in the market. In parallel, pin on disk wear studies were performed. Results are discussed in terms of the different properties and microstructural features of the different ceramic composites.     

A critical review on self-lubricating ceramic-composite cutting tools

Self-lubricating ceramic cutting tools have recently gained considerable attention as the tool wear in cutting hard-to-cut materials greatly affects the production cost, integrity of the machined surface, and productivity. In an attempt to compile the progress made in this important research area, a critical review has been performed covering a range of aspects. These include the current research trends and the need for self-lubricating ceramic tools, identification of prospective high-temperature solid lubricants and their limitations followed by a presentation of recent experimental and numerical work conducted related to self-lubricant ceramic cutting tools. Various lubrication mechanisms involved in the cutting process are also examined to identify general tribological response under various tribo-systems, which is expected to provide useful directions for the researchers and cutting industry. The current and emerging synthesis techniques are discussed in detail and compared with respect to ceramic cutting tools. Finally, some research gaps and future directions are suggested that could lead to optimum design and development of innovative self-lubricating ceramic tools.     

新型陶瓷刀具材料的研究与开发

工业用钢材的质量提高使材料加工难度增加,耐高温的高硬度高强度陶瓷材料被用做切削刀具并逐渐推广应用。本文对陶瓷刀具的材质、种类、性能特点作了比较和评价,并重点介绍了新型的晶须增韧陶瓷刀具。最后,对陶瓷刀具的市场前景进行了预测,并指出了陶瓷刀具研制方面应该深入研究的课题。     

A numerical approach to the heat transfer in monolithic and SiC reinforced HfB2, ZrB2 and TiB2 ceramic cutting tools

Cutting tools are widely used in industry and must be hard enough for machining processes, which should work appropriately at low temperatures to improve cutting speed and productivity. In this research, a numerical method was employed to calculate the temperature distribution in the cutting tools made of different diborides. Monolithic and SiC reinforced HfB₂, ZrB₂ and TiB₂ ceramics were selected for investigation and comparison studies. In this regard, 3-dimensional heat conduction equation was solved in a cutting tool with radiative, convective and heat flux boundary conditions by finite element method using COMSOL Multiphysics. This study clarifies that the maximum temperature in the tools made of ZrB₂ and TiB₂ among the monolithic ceramics is lower than that of HfB₂. Moreover, the temperature variation slope versus time is the highest in HfB₂. All composite materials reinforced with SiC showed lower maximum temperature than the monolithic ones. The thermal performance of TiB₂–SiC and ZrB₂–SiC composites was acquired to be better than that of the other investigated materials. The dominant heat transfer mechanism in the cutting tools was conduction.