Influence of Surface Layer Condition of Al2O3+TiC Ceramic Inserts on Quality of Deposited Coatings and Reliability during Hardened Steel Milling

The specific features of the destruction of tool ceramics, associated with structural heterogeneity and defects formed during diamond grinding, largely determine their reduced reliability (dispersion of resistance). This is most pronounced at increased heat and power loads on the contact surfaces and limits the industrial application of ceramic cutting tools. The surface layer of industrially produced Al2O3+TiC cutting inserts contains numerous defects, such as deep grooves and torn grains. During the milling of hardened steels of the 100CrMn type with increased cutting parameters, the “wear–cutting time” curves have a fan-shaped character with different wear rates. The resistance of the tool that was taken from one batch before reaching the accepted failure criterion has a significant variation in values (VarT is 30%). The study is aimed to evaluate the influence of the condition of the surface layer of Al2O3+TiC inserts processed by various types of abrasive treatments, such as diamond grinding, lapping and polishing, on the quality of the (TiAl)N and (TiZr)N coatings and the reliability of prefabricated end mills. The obtained “wear–cutting time” curves are characterized as closely intertwined bundles. The coefficient of resistance variation (the tool’s reliability) decreases by more than two times (14%). This can be used further in coating development to improve the performance of CCT

Study of the Influence of Silicon-Containing Diamond-like Carbon Coatings on the Wear Resistance of SiAlON Tool Ceramics

DLC coatings have low adhesive bond strength with the substrate and a high level of residual stresses. This paper is devoted to researching a complex of characteristics of a DLC-Si coating deposited on samples of SiAlON ceramics with intermediate coatings (CrAlSi)N pre-formed to improve the adhesive bond strength employing vacuum-plasma spraying. DLC-Si coatings were formed by chemical vapor deposition in a gas mixture of acetylene, argon, and tetramethylsilane supplied through a multichannel gas purge system controlling the tetramethylsilane volume by 1, 4, 7, and 10%. The SiAlON samples with deposited (CrAlSi)N/DLC-Si coatings with different silicon content in the DLC layer were subjected to XPS and EDX analyses. Tribological tests were carried out under conditions of high-temperature heating at 800C. The nanohardness and elasticity modulus of the rational (CrAlSi)N/DLC-Si coating with Si-content of 4.1% wt. were 26 ± 1.5 GPa and 238 ± 6 GPa, correspondingly. The rational composition of (CrAlSi)N/DLC-Si coating was deposited on cutters made of SiAlON ceramics and tested in high-speed machining of aircraft nickel-chromium alloy compared to uncoated and DLC-coated samples. The average operating time (wear resistance) of (CrAlSi)N/DLC-Si(4.1% wt.)-coated end mills before reaching the accepted failure criterion was 15.5 min when it was 10.5 min for the original cutters

Comprehensive analysis of internal and surface defects of ceramics

System approach to studying of causes of infringement of operational characteristics tool ceramic materials on the basis of complex researches and systematization of their volume and superficial defects is presented in article. The main directions of improvement of tool ceramics are allocate

Comprehensive analysis of internal and surface defects of ceramics

System approach to studying of causes of infringement of operational characteristics tool ceramic materials on the basis of complex researches and systematization of their volume and superficial defects is presented in article. The main directions of improvement of tool ceramics are allocate

Investigation of Surface Layer Condition of SiAlON Ceramic Inserts and Its Influence on Tool Durability When Turning Nickel-Based Superalloy

SiAlON is one of the problematic and least previously studied but prospective cutting ceramics suitable for most responsible machining tasks, such as cutting sophisticated shapes of aircraft gas turbine engine parts made of chrome–nickel alloys (Inconel 718 type) with increased mechanical and thermal loads (semi-finishing). Industrially produced SiAlON cutting inserts are replete with numerous defects (stress concentrators). When external loads are applied, the wear pattern is difficult to predict. The destruction of the cutting edge, such as the tearing out of entire conglomerates, can occur at any time. The complex approach of additional diamond grinding, lapping, and polishing combined with an advanced double-layer (CrAlSi)N/DLC coating was proposed here for the first time to minimize it. The criterion of failure was chosen to be 0.4 mm. The developed tri-nitride coating sub-layer plays a role of improving the main DLC coating adhesion. The microhardness of the DLC coating was 28 ± 2 GPa, and the average coefficient of friction during high-temperature heating (up to 800 °C) was ~0.4. The average durability of the insert after additional diamond grinding, lapping, polishing, and coating was 12.5 min. That is superior to industrial cutting inserts and those subjected to (CrAlSi)N/DLC coating by 1.8 and 1.25 times, respectively

Advances in Laser Materials Processing

Today, laser processing is becoming more and more relevant due to its fast adaptation to the most critical technological tasks, its ability to provide processing in the most rarefied and aggressive mediums (e [...

Development and research of vacuum-plasma composite coatings for increase of operability of shearing dies

The technological principles of low-temperature deposition of multilayer vacuum-plasma coatings with the increased operational properties on various types of die steels with the assistance of accelerated argon molecules beam are offered in the article. Four standard architecture of vacuum-plasma coatings - Ti/(Ti,Zr)N, Cr/CrN, TiN/TiCN/(Ti,Cr)N and Ti/(Ti,Al)N are considered. It is shown that deposition of vacuum-plasma coatings of the listed structures at the optimum modes considerably reduces intensity of wear of shearing dies therefore quality of shaped products several times increases

Advances in Laser Materials Processing

Today, laser processing is becoming more and more relevant due to its fast adaptation to the most critical technological tasks, its ability to provide processing in the most rarefied and aggressive mediums (e [...

Use of laser ablation for formation of discontinuous (discrete) wear-resistant coatings formed on solid carbide cutting tool by electron beam alloying and vacuum-arc deposition

A technological process of solid carbide cutting tool surface treatment by selective laser ablation of wear-resistant coating is described. Discontinuous coating is achieved by laser ablation of pre-deposited complex coating, formed by NbHfTi electron beam alloying with subsequent vacuum arc (TiAl)N coating. It is shown that this treatment helps to slow down the wearing process of cutting inserts on their rake and flank surfaces, thus increasing the tool lifetime

Research of the cutting of materials used in heavy power engineering by means of the carbide cutting tools with nanoscale wear-resistant coating

The paper presents the results of the studies focused on the specifics of cutting of materials, used in manufacturing of heavy power engineering products, on the example of longitudinal turning of steel 9SiMn16. To improve such important parameters of cutting as tool life and reliability of carbide tools, it is proposed to use nanoscale multilayer composite coatings, in particular, Ti-TiN-(TiCrAl)N and Zr-ZrN-(ZrNbCrAl)N, produced using the filtered cathodic vacuum arc deposition (FCVAD). It was found out that the use of carbide tools with developed coatings results not only in reduction of cutting forces by 20-25%, but also in substantial reduction of force variation as compared with the corresponding parameters for uncoated tools, which allows improvement of cutting quality. The proposed nanoscale multilayer composite coatings provide significant increase in tools useful life as compared with the standard TiN coating