Study on Coating Mechanism and Properties of Die CrN+DLC Layer

This paper introduces the principle of PACVD coating technology, technical characteristics, equipment composition and material characteristics of CrN+DLC. Taking H13 steel as the research object, its surface was treated with CrN+DLC. The microstructure, bonding state and hardness of the interface were studied by means of metallography, SEM, hardness and component distribution of the surface layer. The anti-crack ability and grade of DLC layer were analyzed by studying the shape of crack distribution with Rockwell hardness indentation, and the high quality layer with crack grade of HF1 was obtained. With the dual properties of diamond and graphite of DLC, it can make the die surface have lower friction coefficient, higher hardness, higher impact toughness, better solid lubrication performance and higher corrosion resistance. Surface DLC coating technology provides a new solution to improve the performance of the die.

Influence of High Temperature Annealing on Microstructure Evolution of Ni-24Fe-14Cr-8Mo Superalloy

The effect of high temperature annealing on microstructure evolution of Ni-24Fe-14Cr-8Mo alloy was investigated through Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Rockwell Hardness Testing Machine. Three kinds of grain growth patterns were found at different annealing temperatures due to carbides precipitation and dissolution. After a combination of high temperature annealing and aging treatment, the hardness versus time curves performed a parabolic pattern. The highest hardness was achieved under 1070°C/60 minutes treatment, and the desirable annealing time should be 60 minutes to 90 minutes.

The Effect of Solidification Rate on the Microstructure and Mechanical Properties of Pure Magnesium

Magnesium, Mg, has been widely investigated due to its promising potential as magnesium alloys for various applications, particularly as biomedical implantation devices among other medical applications. This work investigates the influence of different cooling rates on the strength of pure Mg. The cooling rates were set to cover a low cooling rate LCR (0.035 °C/s) in an insulated furnace, a moderate cooling rate MCR (0.074 °C/s) in uninsulated-ends furnace, and a high cooling rate HCR (13.5 °C/s) in liquid CO2. The casting process was accomplished using a closed system of melting and cooling due to the reactivity-flammability of magnesium in order to minimize processing defects and increase the safety factor. The as-cast samples were metallographically examined for their microstructure, and properties such as impact strength, hardness, and tension were determined. Increasing the solidification rate from 0.035 °C/s to 0.074 °C/s increased the hardness from 30 to 34 Rockwell Hardness and the UTS from 48 to 67 MPa. A higher solidification rate of 13.5 °C/s further enhanced the hardness to 48 Rockwell Hardness and the UTS to 87 MPa in comparison to the 0.074 °C/s cooling rate. Additionally, the fracture behavior and morphology were investigated. It was found that in general, the mechanical properties tended to improve by refining the grain structure.

Optimization of Reinforced Aluminium Scraps from the Automobile Bumpers with Nickel and Magnesium Oxide in Stir Casting

Here, the investigation is spotlighted on the aluminium alloy from the waste materials of the automobile bumpers which is a reinforced metal matrix composite created with 5 percentage of nickel and 5 percentage of magnesium oxide through the stir casting method. The stir casting process inputs parameters such as pressure of squeezing, time of squeezing, and speed of stirrer which were optimized based on the two mechanical properties’ outcome such as the tensile strength (TS) and Rockwell hardness. There are nine different experiments which were conducted based on the L9 array. The Taguchi method is used to identify the optimum input values for the greatest result of the processing condition by Minitab software. The responses-based parameters were ordered based on the rank identified through the investigational effects. Finally, the optimized input consideration values and the linear equations are recommended for both the considered outputs as conclusions.

PEMANFAATAN SERAT PELEPAH KELAPA SAWIT SEBAGAI BAHAN PEMBUATAN KAMPAS REM SEPEDA MOTOR

Brake pads are generally made of asbestos, which is less environmentally friendly and widely available in nature, therefore motorcycle brake pads are made that utilize palm frond fibers filled with alumina powder and bonded to a polyurethane matrix. This research was conducted at the Laboratory of Material Testing of Industrial Chemical Technology Polytechnic (PTKI) Medan. Research was carried out from February-July 2020, using two test, namely the Rockwell Hardness level test and the Pin On Disk Friction Coefficient test. The result showed that oil palm frond fibers can be made into motorcycle brake pads with the addition of alumina powder according to the predetermined composition. After going through the test, the Rockwell hardness level was obtained in A2 treatment (6% Alumina) with the highest and best hardness level, namely 52.75 Kg. And after testing the friction coefficient of the Pin On Disk type, brake pads from palm frounds with the addition of alumina powder composition which have the lowest coefficient value of the best are obtained in treatment A2 (6% Alumina) with a value of 0.000765 N/mm2. Keywords : biocomposite, brake shoes, palm fround fibers, alumina powder

Polylactide and its Composites on Various Scales of Hardness

Polylactide (PLA) has become a widely applied material. Its hardness property has, however, not been a subject of intense study. This study attempts to examine the hardness values of Polylactide and its composites on ten hardness scales. Polylactide composites were developed using three reinforcements (i.e., chitosan, chitin, and titanium powders). The compositing method was the melt-blending technique. Vickers microindentation test was carried out on all the developed samples. The experimental values obtained were related to nine (9) other scales of hardness via an online reference interface. Results showed that the Brinell and Rockwell hardness scales agreed, to a large extent, with the experimental values from several studies. Hence, this work can serve as a reference material on the Brinell and Rockwell hardness values of the unreinforced and reinforced composites considered in this study. The developed materials were also represented on the Mohs scale of hardness with unreinforced PLA having the least value of hardness which corresponds to the value of gypsum on the Mohs scale while the PLA reinforced with 8.33 weight (wt.) % of titanium powder has the highest value of hardness corresponding to the value of a material in-between calcite and fluorite. The hardness values obtained on Shore scleroscope could not agree with the experimental values from various studies. Succinctly, the three particulate fillers increased the hardness properties of PLA. The results of this study would go a long way in helping industrialists and researchers in the correct applications of PLA and its composites.

Polylactide and its Composites on Various Scales of Hardness

Polylactide (PLA) has become a widely applied material. Its hardness property has, however, not been a subject of intense study. This study attempts to examine the hardness values of Polylactide and its composites on ten hardness scales. Polylactide composites were developed using three reinforcements (i.e., chitosan, chitin, and titanium powders). The compositing method was the melt-blending technique. Vickers microindentation test was carried out on all the developed samples. The experimental values obtained were related to nine (9) other scales of hardness via an online reference interface. Results showed that the Brinell and Rockwell hardness scales agreed, to a large extent, with the experimental values from several studies. Hence, this work can serve as a reference material on the Brinell and Rockwell hardness values of the unreinforced and reinforced composites considered in this study. The developed materials were also represented on the Mohs scale of hardness with unreinforced PLA having the least value of hardness which corresponds to the value of gypsum on the Mohs scale while the PLA reinforced with 8.33 weight (wt.) % of titanium powder has the highest value of hardness corresponding to the value of a material in-between calcite and fluorite. The hardness values obtained on Shore scleroscope could not agree with the experimental values from various studies. Succinctly, the three particulate fillers increased the hardness properties of PLA. The results of this study would go a long way in helping industrialists and researchers in the correct applications of PLA and its composites.

Machinability, Hardness and Impact Behavior of Hybrid Fiber Reinforced Composites

Hybrid fabrics are represented by their excellent mechanical and structural properties as compared to conventional metals, which results in their increased functions especially for structural, aerospace applications, automotive, defense as well as sporting industries. In this paper the hybrid fabric (Jute, glass, carbon, Kevlar) composites are prepared by hand layup method and then vacuum bagging is used to avoid voids. The hardness, impact and machinablity test are performed by Rockwell hardness testing machine, Impact testing machine and Drill tool dynamometer respectively. From the results it has been observed that different parameter affects the hardness, toughness and machining of composites

Effects of ball milling on powder particle boundaries and properties of ODS copper

Al2O3 dispersion-strengthened (ODS) copper has an excellent comprehensive performance due to the strong hindrance of the high concentration nano-Al2O3 to the dislocations inside copper grains. However, the processability of ODS copper is seriously deteriorated, which is caused by the presence of unfavorable microlevel Al2O3 particles along powder particle boundaries. In this study, a strategy of ball-milling-induced impurity removal is adopted to surmount the dilemma. It was found that the ball milling process can significantly weaken the formation of large Al2O3 particles in the primary boundaries. However, due to the activation of the powder particle surface, the metallurgical bonding between the powder particles is strengthened. The results showed that the ball-milled samples exhibited the optimal properties, including the ultimate tensile strength of 488 ± 3 MPa, elongation of 18.7 ± 0.7%, reduction in the area of 46.8 ± 1.2%, 82.2 ± 0.3 Rockwell Hardness measured on the B scale (HRB), and electrical conductivity of 77.2 ± 0.1% International Association of Classification Societies (IACS).