Solid State Phenomena Vol. 354

Abstract: Direct diamond deposition on a steel surface has been considered very difficult. Recently, we found that high-quality diamond films can be deposited on the surface of stainless-steel X5CrNi 18-10 by drilling multiple regularly arranged pits without interlayers or seeding. The following two hypotheses (A) and (B) can be considered as the reason why a high-quality diamond film can be deposited: (A) unoxidized Cr and Ni exposed to the stainless-steel X5CrNi 18-10 surface prevent carbon diffusion into interior of the stainless-steel, resulting diamond core generation, (B) Surface geometry with regular roughness contributes to stress relaxation and delamination prevention. In the present study, those hypotheses have been examined by quantum chemistry calculation and experimental. For the quantum chemistry calculation, energy barrier and kinetic energy for a carbon atom intrudes into a model cluster has been calculated with an ab-initio computational chemistry software package, Gaussian. The calculation result has supported hypothesis (A). For the experiment, X5CrNi 18-10 stainless-steel substrates with different surface characteristics are prepared by using various mechanical machining methods and used in the direct deposition process for diamond with in-liquid plasma CVD. The experimental result has supported both hypothesis (A) and (B).

Abstract: Tool wear is an important problem when cutting hard-to-cut materials such as stainless steel and nickel alloys. This unignorable disadvantage is caused by the diffusion of dissociated carbon atoms to the surface layer of the tool tip during the cutting process, and this has been confirmed by SEM/EDS analysis of worn tool tips. In this study, a novel cutting method is proposed in which chemically activated H₂O molecules are introduced to the cutting tool tip in order to prevent tool wear by removing dissociated carbon atoms on the surface layer of the tool tip. In cutting experiments, stainless steel X5CrNi 18-10 (JIS SUS304), a cemented carbide tool tip, cutting oil, steam, and Ar plasma were used. Ar plasma was used for raising the steam temperature around the tool tip and chemically activating H₂O molecules. From the results, the dissociated carbon and constituted knife edge were mostly removed by H₂O steam and cutting oil without Ar plasma. However, in some cases using Ar plasma, the workpiece melted and tightly adhered to the cutting face of the tool tip. This suggests that the H₂O steam temperature should be suitably controlled so as to remove carbon atoms effectively from the cutting face of the tool tip.

Abstract: This research aims to study the electropolishing conducted under vacuum status. The electropolishing can be used to finishing high purity components of SUS 316L to make them shine and without leaving residual stress, micro-cracks, etc. In the research, the electropolishing process parameters are selected, such as current density, degree of vacuum and polishing time to conduct the electropolishing experiment. The experimental results show that the bubbles attached to the surface of the work-piece in the vacuum state are reduced, thereby improving the surface roughness and surface pitting. The vacuum status in the process can improve the electropolishing process.

Abstract: A novel edge treatment method that utilizes a tip-burnishing process with an active rotary tool developed by the authors was proposed. Two types of burnishing process experiments were conducted using the tip-burnishing process to deburr the workpiece edge and create a sharp cutting edge. Furthermore, an evaluation test for the cutting performance of the sharp edge, which was treated using the developed burnishing process, was conducted. In the deburring experiment, superior deburring was achieved by generating a sliding effect orthogonal to the burr generation direction. An experiment was conducted for evaluating the sharpening of the cutting edge; it was observed that the cutting-edge angle decreased due to the burnishing process. A cutting performance test was conducted using a wedge-shaped workpiece before and after burnishing. The cutting performance of the workpiece was quantitatively evaluated based on the load and stroke required for the cutting of the sheet material.

Abstract: Electropolishing has been widely used for surface finishing of metallic products in the industry, owing to its excellent capability of producing metallic components with a homogeneously smooth surfaces. However, this treatment is often constrained by the long duration required for the processing. Therefore, an improvement in this process is needed. The aim of this research is to introduce the use of electropolishing with circulated electrolytes for improving the surface finish of brass. In this work, electropolishing was carried out by using circulated H₂SO₄ electrolyte for 10 to 30 min in a customized electropolishing chamber. The effect of this treatment on surface morphology, surface roughness, and thickness reduction of the brass specimen was determined. The results showed a better capability of electropolishing with circulated electrolyte in decreasing the brass roughness, i.e., by 84%, than that without electrolyte circulation which only reached 45% during 30 min of the treatment.

Abstract: The nosecone tip during the launch process becomes the first part that experiences friction against the atmosphere so that heat is generated, which continues to increase over time. Therefore, the nosecone tip material must have high-temperature resistance, and the materials used must not interfere with the avionics and telemetry systems of the rocket. When the sounding rocket orbits at an altitude of 200-300 Km, the atmospheric environmental conditions also fluctuate, so the nose cone tip must also be able to adapt to this condition. The end of the nose cone must be protected with a high heat-resistant Thermal Barrier Coating (TBC) coating using Yttria Stabilized Zirconia (YSZ). YSZ modified with Al₂O₃ has impressive performance against high thermal by increasing the temperature resistance of the substrate to about 1200°C. In this paper, the experiment done for the first time using Hastelloy C276 coated with YSZ with thermal spray method has shown good performance. The pull of test results shows the highest bond tensile strength after heat exposure value at 23,04 MPa. And the thermal torch testing resulted in mass decreasing by 0.493 grams at 1200°C. The vector analyser also offers good performance reflection loss, valued at -0.324 dB at 10 GHz, and the thermal gravimetry of the material tip nose is 93,2% at 1200°C.

Abstract: This study observed the results of plasma nitrocarburizing processes on JIS SKD61 Steel. This research aims to use a plasma nitrocarburizing process to increase the hardness and wear resistance of JIS SKD61Steel. Before plasma nitriding was carried out, the sample had undergone a pre-treatment process. The optimum hardness value obtained after the pre-treatment process was 504 HV. The optimum hardness obtained in the plasma nitrocarburizing sample was 830 HV at temperatures 500°C for 4 hours. The optimum wear resistance or specific wear results on plasma nitrocarburizing was 0.11 x10^-6mm²/kg at temperatures 400°C for 4 hours and 0.08 x10^-6mm²/kg at temperature 500°C for 4 hours. XRD test results show that the phase formed in the nitrocarburizing compound layer was the iron nitride, iron carbonitride FeN, FeN_0.49, ε-Fe_2-3N, or ε-Fe_2-3(N,C). The process of plasma nitrocarburizing has improved the mechanical properties of hardness and wear resistance of SKD61 steel.

Abstract: Using of metal matrix composite coating is a promising approach for improving the surface properties of a component against the mechanical and environmental attacks especially wear and corrosion. Laser cladding (LC), also known as direct energy deposition (DED), is an additive manufacturing (AM) technique, able to perform coating, repair worn parts, manufacturing and prototyping. In this work, pure Al and a mixture of multi-ceramic Al-15SiC-15Al₂O₃ coatings were successfully deposited on Al-based substrate. The quality of the deposited clads was evaluated according to macro-graphic, microstructure, and microhardness characteristics. The microscopic inspection of the multi-ceramic coatings showed a slight dilution of SiC particles. Also, XRD investigation revealed a formation of Al₄C₃ carbide. Besides SiC and Al₂O₃ hard phases, this yielded an increase in matrix microhardness about 180% (from 75 to 212 Hv_0.05) as compared to pure Al clads, indicating a great improvement in the mechanical properties of the composite cladded coating.

Abstract: Although the Incremental Sheet Forming (ISF) technology has been studied and applied from the last decade of the previous century with more than 30 years of experiences and ameliorations of the researchers of this field, but the ability of deformation of the formed material sheet still has remained in a restrictive modest value. This sheet forming technology could be divided into 2 mains branches: Single Point Incremental Forming (SPIF) and Two Point Incremental Forming (TPIF) wherein the first one is usually applying in research and the second branch is used in production. The ISF is suitable for forming sheet for a single product or for small batch production with a great advantage of a no-need pestle and mold manufacture in advance, but the formability of formed sheet material cannot bigger than a limited formed angle of about 80^o that depends on the material and the forming parameters. There are some ameliorations for increasing the formability of the formed sheet such as heating the formed sheet in Hot SPIF or Multistage SPIF (MSPIF)… All the effort and amelioration measures are confronted with different difficulties. In this paper, we concentrate to study on the MSPIF technology on stainless steel SUS304 by simulation method with the proof of experimental method. The results were also compared to the simple SPIF to show its own pros and cons on the related field such as the technology, the productivity and the lubrication.