Electrical Discharge Machining of Alumina Using Ni-Cr Coating and SnO Powder-Mixed Dielectric Medium

Okunkova, Anna A.; Волосова, М. А.; Kropotkina, E. Yu.; Hamdy, Khaled; Grigoriev, Sergey N.

doi:10.3390/met12101749

Cited by 8 publications

(13 citation statements)

References 82 publications

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“…The machine enables the use of any type of working medium (water-or oil-based) [52]. The chosen range of factors based on [52,53] is presented in Table 3. The operational current was 0.3-0.4 A [53].…”

Section: Microtexturing Using Electrical Discharge Machiningmentioning

confidence: 99%

“…The chosen range of factors based on [52,53] is presented in Table 3. The operational current was 0.3-0.4 A [53]. Variations of two technological factors, pulse frequency f and duration D, were chosen for the experiments.…”

Section: Microtexturing Using Electrical Discharge Machiningmentioning

confidence: 99%

“…It should be noted that any conductive coating can be used to provide conductivity to the outer layer on the surface of the insulating sample. Our research group has devoted a few studies to this; we proposed using a Ni-Cr coating (plasma vapour deposition), which has an effect on the electrical discharge machining ability of aluminum oxide [53], and a Cu-Ag multilayer sandwich coating also showed remarkable results in the electrical discharge machining of Al 2 O 3 [38,39]. All possible options for the wide range of insulating ceramics are provided in [41].…”

Section: Multifunctional Coatingmentioning

confidence: 99%

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Simulation of Mechanical and Thermal Loads and Microtexturing of Ceramic Cutting Inserts in Turning a Nickel-Based Alloy

Волосова

Okunkova

Hamdy

et al. 2023

Metals

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This paper is devoted to the problem of wear resistance in square Si3N4 ceramic cutting inserts, which exhibit high hardness and strength, in combination with brittleness, in machining super alloys (e.g., a nickel-based alloy of Inconel 718 type) for aviation purposes, when subjected to increased mechanical and thermal loads. Microtextures were proposed to reduce the intensity of the contact loads on the pad between the cutting edge and the workpiece. The simulation of the mechanical and thermal loads demonstrated the superior ability of the faces with the preformed microgrooves (125 µm in width) compared to microwells (ø100 µm). The tense state was 4.97 times less, and there were 2.96 times fewer deformations. It was shown that they hamper the development of thermal fields at 900 °C. Two types of microtextures (210 µm-wide microgrooves and microwells 80 µm in diameter) were produced on the rake faces of the cutting inserts via an innovative and integrated approach (the electrical discharge machining of dielectrics using multifunctional and TiO2-assisted powder), and a conductive and wear-resistant TiN coating was deposited via magnetron vacuum plasma sputtering (95%N2/5%Ar). The failure criterion in turning was 400 µm. An increase of 30% in tool wear resistance was demonstrated.

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Section: Microtexturing Using Electrical Discharge Machiningmentioning

confidence: 99%

Section: Microtexturing Using Electrical Discharge Machiningmentioning

confidence: 99%

Section: Multifunctional Coatingmentioning

confidence: 99%

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Simulation of Mechanical and Thermal Loads and Microtexturing of Ceramic Cutting Inserts in Turning a Nickel-Based Alloy

Волосова

Okunkova

Hamdy

et al. 2023

Metals

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“…Under the trend of intelligent manufacturing, automatic quality control is widely regarded as the top priority in industrial production [ 1 , 2 ]. Surface defect, the key factor of quality control, is generally defined as local anomalies embedded in homogeneous textures [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

Weighted Matrix Decomposition for Small Surface Defect Detection

2022

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Detecting small defects against a complex surface is highly challenging but crucial to ensure product quality in industry sectors. However, in the detection performance of existing methods, there remains a huge gap in the localization and segmentation of small defects with limited sizes and extremely weak feature representation. To address the above issue, this paper presents a weighted matrix decomposition model (WMD) for small defect detection against a complex surface. Firstly, a weighted matrix is constructed based on texture characteristics of RGB channels in the defect image, which aims to improve contrast between defects and the background. Based on the sparse and low-rank characteristics of small defects, the weighted matrix is then decomposed into low-rank and sparse matrices corresponding to the redundant background and defect areas, respectively. Finally, an automatic threshold segmentation method is used to obtain the optimal threshold and accurately segment the defect areas and their edges in the sparse matrix. The experimental results show that the proposed model outperforms state-of-the-art methods under various quantitative evaluation metrics and has broad industrial application prospects.

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“…After processing, the film can be chemically removed from the ceramic surface with acetone, K 2 CrO 4 -H 2 SO 4 mixture, or other solvents [60,61]. There are several types of coating to accomplish the process, such as copper assisting electrode [56,[62][63][64][65], silver varnish [45,64], carbon conductive layer [66], multimaterial sandwich coatings [64,67], and Ni-Cr coating by plasma vapor deposition [68]. The assisting electrode made of copper tape can be removed easily from the AlN [64], Al 2 O 3 [65], and ZrO 2 [69] ceramic surface after the machining.…”

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confidence: 99%

Advances in Electrical Discharge Machining of Insulating Ceramics

Grigoriev,

Volosova,

Okunkova

2023

Materials

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There are two main ways of carrying out the electrical discharge machining of the insulating ceramics: changing the electrical and chemical properties of ceramics due to additives in producing composites/nanocomposites and changing the electrical and chemical properties in the interelectrode gap. This review summarizes and analyzes the current data on the machinability in water suspension and hydrocarbons depending on the electrical properties of the ceramic composites and assisting means such as coating and powder. There are provided the existing approaches and original methods for solving the global problem of the electrical discharge machining of insulating ceramics, suggesting further development of the existing methods since, up to now, the experimental research is non-systemic. The dependencies of the machinability on the electrical properties of conductive ceramic composites, the specific electrical resistance of the assisting coating, and the assisting powder’s band gap and concentration for machining insulating ceramics are revealed. The higher the electrical conductivity, the higher the machinability of ceramic composites, and the lower the band gap, the higher the machinability for insulating ceramics. Two technological gaps were revealed in the powder’s concentration that can be a particular case of logarithmic decrement of attenuation. The proposed approach suggests using assisting powder with the lower band gap.

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Electrical Discharge Machining of Alumina Using Ni-Cr Coating and SnO Powder-Mixed Dielectric Medium

Cited by 8 publications

References 82 publications

Simulation of Mechanical and Thermal Loads and Microtexturing of Ceramic Cutting Inserts in Turning a Nickel-Based Alloy

Simulation of Mechanical and Thermal Loads and Microtexturing of Ceramic Cutting Inserts in Turning a Nickel-Based Alloy

Weighted Matrix Decomposition for Small Surface Defect Detection

Advances in Electrical Discharge Machining of Insulating Ceramics

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