Composition, microstructure and mechanical properties of boron containing multilayer coatings for hot forming tools (original) (raw)
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Boron containing combination tool coatings—characterization and application tests
Thin Solid Films, 2006
The requirements for durable tool coatings continuously increase. In many cases, tool coatings combining different phases or several layers could provide an improvement in tool life. The broad range of mechanical properties of materials in the B -C -N and Ti -B -N ternary systems, from very soft to superhard, presents many possibilities to generate various combination coatings. Such coatings were prepared using reactive sputter techniques with different target materials. An outstanding example is a superhard 3 Am thick coating system with a 0.5 to 0.8 Am thick cBN top layer deposited on cutting inserts. Soft coatings like hexagonal boron nitride were found to be essential for machining operations under dry conditions. The coatings were characterized with respect to hardness, abrasive wear rate and friction coefficients. The correlation between properties and composition was revealed. Application test results of B -C -N and Ti -B -N coating systems on tools obtained under near production conditions will be reported. Specifically, turning tests performed with cemented carbide cutting inserts coated with a superhard coating system with a cBN top layer will be discussed. D
Wear, 2012
In this study, the high temperature wear behavior of hot forming tool steel grades is investigated by successive sliding of a pre-alloyed Usibor1500P s strip heated at high temperature. Experimental tests are performed at high temperature on an instrumented Deep-Drawing Process Simulator (DDPS). This laboratory pilot is employed to rank different steel grades used as tool materials in the hot-stamping process. The wear damage of the tool (die radius) is characterized by profilometry and SEM observations, and three quantitative criteria are determined from 2D profile measurements to assess adhesive and abrasive wear. Under examined conditions at high temperature, a predominant transfer mechanism is observed, while abrasive wear appears as minor damage. When the surface hardness of the tool material is not great enough, the sub-surface of the die radius can exhibit a plastic shear deformation of about 10 mm in depth. This leads to emission of wear debris coming from the cumulated cyclic plastic deformation of the sub-surface. In contrast, for high surface hardness, the adhesive wear rapidly reaches an asymptotic state.
Effects of the gas mixture on the characteristics of PACVD TiN coating of hot-work tool steel
DESCRIPTION Titanium nitride (TiN) coatings were deposited on hot-work steel (DIN 1.2367) by plasma-assisted chemical vapor deposition (PACVD) and the influence of different N 2 /H 2 gas flow ratio on the layer properties were investigated. Scanning electron microscopy studies shows that the growth rate increases with increasing N 2 /H 2 gas flow ratio. It was learned the TiN layers are nearly stoichiometric, except for low N 2 gas flows. Grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM) and pin-on-disk test were used to evaluate the microstructure as well as tribological properties such as friction, wear, and hardness. It was also revealed that by increasing the flow ratio, the grain size of the TiN coatings decrea sed. A hardness of 1710 HV 0.05 was obtained when the layer was fabricated at the higher flow ratios.
Journal of the Korean Physical Society, 2017
With a view to improving the mechanical properties of coatings applied in the field of cutting tools and machine parts, the TiAlBN coatings were deposited by using direction-current (dc) magnetron sputtering with the various contents of nitrogen gas in an argon-nitrogen gas mixture. The structural characteristics of the coatings were determined by using X-ray diffraction, the friction coefficient, and the hardness and elastic modulus of the coatings were investigated by using a tribometer and nano-indentation. The surface morphologies and the roughnesses of the coatings were analyzed by using field emission scaning electron microscopy (FESEM) and atomic force microscopy (AFM). Additionally, the effects of nitrogen gas flow on the properties of the TiAlBN coatings were investigated. The structural characterization results revealed a typical face-centered cubic TiN structure with (111), (220), and (222) diffraction peaks. The strongest intensity in the (111) orientation was obtained for the coating prepared at a nitrogen gas flow of 4 sccm. For this kind of samples were obtained the highest values of the hardness and the stability, a low friction coefficient, and a smooth surface.
Influence of temperature on abrasive wear of boron steel and hot forming tool steels
Wear, 2015
In many industrial applications the occurrence of abrasive wear results in failure and replacement of components. Examples of these applications are found in mining, mineral handling, agriculture, forestry, process and metalworking industry. Some of these applications also involve operation of relatively moving surfaces at elevated temperatures which increases the severity of wear. A typical example of high temperature wear phenomena is that of tool steels during interaction with boron steel in hot forming. Some studies have been carried out regarding the high temperature tribological behaviour of these materials but results pertaining to their high temperature three body abrasive behaviour have not been published in the open literature. In this work, the high-temperature three body abrasive wear behaviour of boron steel and two different prehardened tool steels (Toolox 33 and Toolox 44) was investigated using a high temperature continuous abrasion machine (HT-CAT) at different temperatures ranging from 20°C to 800°C using a load of 45 N and a sliding speed of 1 ms À 1. The wear results were correlated to the hot hardness of the different materials measured by means of a hot hardness tester (HHT) at a load of 10 kgf. Scanning electron microscopy and energy dispersive spectroscopy (SEM/EDS) techniques were used to characterise the worn surfaces. The hot hardness measurements of the three different materials showed a slight but continuous decrease of hardness from room temperature to 600°C. At temperatures above 600°C the hardness showed a sharp decrease. The wear rate of Toolox 44 was constant from 20°C to 400°C. On the other hand, Toolox 33 and boron steel, showed a reduced wear rate from 20°C to 400°C attributed to an increased toughness and the formation of wear-protective tribolayers respectively. At higher temperatures (from 400°C to 800°C), the wear rate for these materials increased mainly due to a decrease in hardness and the occurrence of recrystallization processes.
International Journal of Refractory Metals and Hard Materials, 2002
Cubic Ti(B x C y N z) (x þ y þ z ¼ 1) coatings were deposited on cemented carbides using chemical-vapor deposition (CVD). The Ti-B-C-N was maintained in the cubic phase by keeping the B content below 5%. The B:C:N ratio, microstructure, hardness and wear resistance of the coatings were controlled by varying the gas precursor flows in the CVD process. Results showed that TiCN coatings containing B exhibited higher hardness but lower critical loads (L c) for coating decohesion. Microprobe measurements revealed that B diffusion was responsible for inhomogeneous coating compositions and for the formations of a CoWB phase on the surface of the cemented carbide tool. Milling tests showed the coatings had good abrasion wear resistance. The dominant wear mechanism in turning tests was cratering.
Performance of boron nitride coated tools and dies
Advances in Production Engineering & Management, 2013
Boron nitride (BN) has been utilized as a significant coating material for cutting tool applications due to its excellent mechanical and chemical properties. Cutting tools, molds and machine parts are coated with BN with the coating system using a sputtering technology − a physical vapour deposition (PVD) process. Design and manufacture of the equipment is made locally. Physical, mechanical and tribological properties such as thickness, friction coefficient, wear, and adhesion are measured by using calotest, tribometer, profilometer, micro and macro scratch test, and nanohardness devices. The results of characterization of the coatings show that wear resistance and hardness increase and BN coatings provide increased efficiency by creating a value-added manufacturing. In this case, the use of BN-coated tools in machining is expected to be one of the best solutions.
Surface and Coatings Technology
Hexagonal boron nitride (h-BN) coatings prepared from a polyborazylene (PBN) polymeric precursor were deposited on titanium-based substrates and annealed via infra-red irradiation in a rapid thermal annealing (RTA) furnace. Crystallized h-BN coatings were obtained by adding Li 3 N as a catalyst at a relatively low annealing synthesized temperature (~ 1200°C). The resulting coatings had a thickness of 15 µm and were evenly coated and homogenous. The coating/substrate adhesion was evaluated by the micro-scratch test, with the value of best critical load occurring at approximately 12N against a Rockwell C diamond point. This adhesion increased with the growth of the additive ratio of Li 3 N. The friction coefficient measurements were carried-out by tribological testing at 360°C using a cylinder/disk configuration. Stainless steel 15-5PH cylinders were used as counter bodies to the titanium disk. The friction coefficient was reduced from 0.72 for the Ti/stainless tribosystem to 0.35 for the Ti/h-BN/stainless tribosystem.
Dry sliding wear behavior of borided hot-work tool steel at elevated temperatures
Surface and Coatings Technology, 2017
In the present study, the surface of AISI H13 hot-work tool steel was borided with EKabor II powders using powder pack-boriding method. The process was carried out at 800, 900 and 1000 °C temperatures for 2, 4 and 6 h periods. The wear tests were carried out using a ball-on disc tribometer at room temperature and 500 ºC on borided and untreated AISI H13 hot-work tool steel. Scanning electron microscope (SEM), optical microscope, 3D profilometer, X-Ray diffraction analysis and micro-hardness tester were used in the evaluation of micro-structure and wear data. The increase in the boriding temperature and boriding period led to increased thickness and hardness of the boride layer. Boriding at 800 °C resulted with formation of Fe 2 B, Mn 2 B, Cr 5 B 3, phases, while FeB, Fe 2 B, Mn 2 B, and Cr 5 B 3 boride phases occurred at 900 and 1000 °C. Dominant wear mechanisms were microcrack-induced plastic deformation during high temperature wear tests; oxidation and microcrack formation during room temperature wear tests; and oxidation and severe plastic deformation for the untreated specimen.
Materials, 2021
Cutting tools have long been coated with an AlCrN hard coating system that has good mechanical and tribological qualities. Boron (B) and vanadium (V) additions to AlCrN coatings were studied for their mechanical and tribological properties. Cathodic multi-arc evaporation was used to successfully manufacture the AlCrBN and AlCrVN coatings. These multicomponent coatings were applied to the untreated and plasma-nitrided surfaces of HS6-5-2 and H13 steels, respectively. Nanoindentation and Vickers micro-hardness tests were used to assess the mechanical properties of the materials. Ball-on-flat wear tests with WC-Co balls as counterparts were used to assess the friction-wear capabilities. Nanoindentation tests demonstrated that AlCrBN coating has a higher hardness (HIT 40.9 GPa) than AlCrVN coating (39.3 GPa). Steels’ wear resistance was significantly increased by a hybrid treatment that included plasma nitriding and hard coatings. The wear volume was 3% better for the AlCrBN coating tha...