ICMCTF2016 Session GP: Symposium G Poster Session

Cold forging is a manufacturing process which is of great importance due to the maximum degree of material utilization, the associated energy and the resource efficiency in production technology. Commonly, lubricants are applied to reduce friction between workpieces and forming tools in cold forging processes. Due to significant advances in solid lubricant coatings deposited by physical vapor deposition (PVD) in the recent years, coatings took over the tasks of lubricants in numerous applications. However, most attempts to realize dry metal cold forging of steel failed so far. High power pulsed magnetron sputtering (HPPMS) (Cr_1‑xAl_x)N+MoS_y coatings are promising candidates in order to replace lubricants on highly loaded tools in dry cold forging. Wear resistant (Cr_1‑xAl_x)N extended by the self-lubricating MoS_y offers an extension of tool life without lubricants. HPPMS technology offers outstanding advantages in terms of high hardness and dense morphology. In addition to that, complex-shaped forging tools with surfaces oriented non-parallel to the target can be coated by using HPPMS. In the present work (Cr_1-xAl_x)N+MoS_y coatings were deposited on X155CrMoV12 tool steel by means of HPPMS using an industrial scale PVD unit. An especially designed target consisting of a CrAl half and a MoS₂ half in form of triangles was used, which leads to a variation of the chemical composition of the deposited coatings dependent on the substrate position within the coating chamber. Coating thickness and morphology were determined by using Scanning Electron Microscopy (SEM). Transmission electron microscopy (TEM) was used to determine crystal structure. For this purpose, the coating was prepared by means of focused ion beam (FIB). Glow Discharge Optical Emission Spectroscopy (GDOES) was used to analyze the composition. The surface roughness was measured by means of confocal laserscanning microscopy (CLSM). Phase composition was investigated by using X-Ray Diffraction (XRD). Universal hardness HU and indentation modulus E_IT were measured by using nanoindentation. A pin-on-disc tribometer (PoD) was used to simulate the tribological behavior during dry contacts. Decreasing the Mo and S contents by increasing Cr and Al contents leads to considerable influences on the coating properties. It was found that universal hardness and indentation modulus increase with decreasing Mo and S contents. A reduction of the friction coefficient with the addition of Mo and S was observed. The coating (Cr_1-xAl_x)N together with the self-lubricating MoS_y deposited using HPPMS technology has a high potential for lubricant-free cold forging of steel.

Commonly, temperature-induced modifications in the mechanical properties of hard and protective coatings are determined by nanoindentation after heat treatment. We report elastic modulus and hardness values of (Ti_0.55Al_0.45)_0.49N_0.51 at temperatures of up to 600°C, measured by in situ nanoindentation with a Hysitron TI-950 TriboIndenter, equipped with a xSol™ high temperature heating stage. The coatings were deposited onto single crystalline Si (100) and Al₂O₃ (0001) by reactive cathodic arc deposition in an industrial deposition system at 450°C. Prior to nanoindentation tests, the coatings were prepared by chemical mechanical polishing to reduce the surface roughness. Continuous stiffness and hardness measurements were employed to determine the mechanical properties as a function of contact depth. The differences between in situ and ex situ data clearly underline the significance of in situ testing for the investigation of hard and protective coatings.

This paper presents a study of hard coatings obtained by physical vapor deposition PVD applied to components of a mold used for the injection of aluminum. During the experimental development, it was required find out a solution through PVD coating to contribute to the reduction of friction in the mold components and consequently improve the extraction of parts, seen as a negative impact of problem during the casting process. The purpose of this study was to assess PVD coatings, testing three different coatings rich in Aluminum and Chromium. Through these coatings was analyzed its structure and evaluated their performance when subjected to testing in normal production conditions.

One of the fast-growing segments of manufacturing is plastics processing. The properties of plastic products can be optimized by a suitable design of the component surface. One promising method is the usage of molding tools structured in the micrometer range for plastics processing by extrusion and injection molding. Such microstructured, optically functional plastic parts are commonly used in light-field photography, displays and security technology. However, the adhesion of the plastic melt on the mold surface during the processing can shorten the life time of mold inserts under possible abrasive wear and corrosion. Physical vapor deposition (PVD) is a technology for deposition of hard wear resistant coatings on a variety of technical tools and components. PVD hard coatings, such as ternary and quaternary chromium based nitride (Cr_1-xAl_x)N and oxynitride (Cr_1-xAl_x)ON, are used as protective coatings due to their mechanical, chemical and tribological properties to reduce wear, corrosion and adhesion forces between mold insert and plastic.

Within the scope of this paper, oxynitride hard coatings deposited by means of middle frequency pulsed magnetron sputtering (mfMS) on steel substrates AISI 420 were investigated. The oxygen flows F(O₂) = 10 sccm, 15 sccm and 20 sccm were selected due to their high universal hardness HU and indentation modulus E_IT of the coatings. A laser microstructuring was carried out by Institute For Laser Technology with a depth of s = 1,5 µm on the coatings was subsequently performed. The influence of the oxygen content on the coatings morphology and its chemical composition as well as on the mechanical and tribological properties was characterized. With increasing oxygen flow, universal hardness and indentation modulus increased from HU = 8.6 ± 3.1 GPa and E_IT = 189.73 ± 52.9 GPa to HU = 16.8 ± 3.0 GPa to E_IT = 252.27 ± 38.4 GPa. Makrolon® LED2245 was considered for tribological investigations. Adhesion behavior of molten polycarbonate on (Cr_1-xAl_x)ON hard coatings was analyzed by high temperature contact angle measurements. Wear tests were performed by using pin-on-disc-tribometer measurements at room temperature T = 23 °C and higher tempreture T =150 °C against solid Polycarbonate. The coatings were structured successfully by laser and a prosperous deforming could be proofed. The mfMS Cr_0,39Al_0,05O_0,21N_0,35 hard coatings deposited by using an oxygen flow rate of F(O₂) = 20 sccm showed the lowest wear rates due to their higher hardness. The results indicate a high potential of the investigated oxynitride coatings to be used as protective coatings against abrasive and adhesive wear during processing of polycarbonate.

Strained Ge channel N type metal-insulator-semiconductor transistor including the biaxial compressive strain thin Ge film grown on Si substrate by ultra high vacuum chemical vapor deposition is demonstrated, and the performance enhancement experimentally is also exhibited. The drive current and subthreshold swing of strained Ge transistor is better than Si control device. The on-off current ratio is reaching the eight order without sacrificing the leakage current. For the mobility enhancement, Ge device exhibits over 100% enhancement compared with the Si one. To develop strained Ge N type and P type metal-insulator-semiconductor transistor with Ge thin film for CMOS technology without III-V material may have nanoscale feasibility be the future generation and compatible to present CMOS process.

Gear hobbing is the most common cutting process for green manufacturing of gears. The cutting conditions regarding chip thickness and cutting length change continuously within every generating position. Hence, the load at the cutting edge varies critically too and affects abrasive and crater wear on the tool. Nowadays gear hobbing is performed more and more without coolant which intensifies the wear phenomena.

To examine the performance of different coatings, cutting trials were carried out using the well-established fly-cutter analogy test. Subsequently the worn out single hob teeth are examined by REM and fringe projection to evaluate the wear phenomena.

To reduce crater wear and to extend the lifetime of gear cutting tools a range of AlCrN-based coatings was deposited in an industrial π⁴¹¹ rotating arc cathodes PVD unit. Significant performance differences between the chemically and structurally modified coatings were found. Doping the coating top layer with titanium in combination with an optimized nanolayer structure lead to a substantial increase of tool life.

From the results of performance test, it was shown that the Cu film is better than others. This study results also showed that this pre-coated copper film can provide good conductivity and future process of electroplating.