scholarly journals Fabrication of Miniature Components from ZrO2 Powder by Combining Electrical-field Activated Sintering Technique and Micro-forming

2018 ◽  
Vol 190 ◽  
pp. 10007
Author(s):  
Hasan Hijji ◽  
Yi Qin ◽  
Kunlan Haung ◽  
Muhammad Bin Zulkipli ◽  
Jie Zhao
Keyword(s):  
Low Voltage ◽  
Heating Temperature ◽  
Processing Parameters ◽  
Holding Time ◽  
Micro Forming ◽  
High Quality ◽  
Electrical Field ◽  
Activated Sintering ◽  
Zro2 Powder ◽  
Wide Range

There is an increased demand for miniature/micro products (such as MEMS) and nanotechnology-based products (such as nano-materials). Micro-manufacturing is a link between Macro-and Nano Manufacturing and an effective means for transferring nanotechnology-product designs into volume production. The micro forming has the potential for low-cost, high volume manufacturing applications. In order to meet the high demands on miniaturised products, a rapid production technique and the system, high flexibility, cost-effectiveness and processing a wide range of materials are needed. Recently, a series of studies have been undertaken to investigate forming miniature/micro-components by using a combination of micro-forming and Electrical-field activated sintering (Micro-FAST). The process uses low voltage and high current density, pressure-assisted densification and synthesis technique, which renders several significant merits. The work to be reported in this paper will be focused on the forming of miniature components from Zirconia (ZrO2) powder, without using binders. Several processing parameters have been investigated, such as pressure, heating rate, heating temperature and holding time, which helped to obtain high-quality parts. Using graphite dies and punches, sample parts (solid cylinders of Ø4.00mm × 4.00 mm) were formed. These were subjected to detailed examinations and analysis, such as analysis of the relative density, hardness at the necks formed among the particles and in the particle bodies, as well as the microstructures. The results showed that directly forming the parts from loose powder is feasible, and by properly designing and control the processing parameters, high-quality parts could be achieved, among which heating temperature and holding time are extremely important. At the same time, due to low conductivity of the powder material, carefully designing the tooling is essentials for ensuring properly heating, pressurisation and cooling.

Simulation Research of the Effect of Thermal Reflow Processing Parameters on the Profile of Micro-Spherical Structure

2011 ◽  
Vol 239-242 ◽  
pp. 517-523 ◽  
Author(s):  
Bing Yan Jiang ◽  
Lei Chen ◽  
Dai Bing Li ◽  
Stefan Kirchberg
Keyword(s):  
Heating Rate ◽  
Heating Temperature ◽  
Orthogonal Experiment ◽  
Three Dimensional ◽  
Processing Parameters ◽  
Holding Time ◽  
Cylindrical Shape ◽  
Optimum Processing ◽  
Spherical Structure ◽  
Experiment Method

In this paper reflow process is integrated into LIGA process in order to realize three dimensional fabrication. The melting and deformation process of photoresist, which has an initial cylindrical shape of D500μm and h66μm, and the influence of various processing parameters on the height of formed microlens, is simulated with Marc. The optimum processing parameters combination is obtained by orthogonal experiment method and the influence of different processing parameters on the height of micro-spherical structure is studied with single factor experiment method. The results showed that the optimum processing parameters combination was 1°C /s for heating rate, 110°C for heating temperature and 45min for holding time; the significance of processing parameters on the micro-spherical structure’s height can be ordered in holding time＞heating rate＞heating temperature.

The effect of thermal processing parameters on the mechanical properties of aluminium alloy foam

2018 ◽  
Vol 1 (91) ◽  
pp. 12-17
Author(s):  
D. Puspitasari ◽  
T.L. Ginta ◽  
P. Puspitasari ◽  
M. Mustapha
Keyword(s):  
Mechanical Properties ◽  
Aluminium Alloy ◽  
Thermal Processing ◽  
Heating Temperature ◽  
Processing Parameters ◽  
Holding Time ◽  
Vacuum Furnace ◽  
Closed Cell ◽  
Stress Relieving ◽  
Stabilization Temperature

Purpose: The purpose of this study was to investigate the influence of three thermal processing parameter called stress relieving on mechanical properties of the aluminium alloy foam. Design/methodology/approach: The samples were undergone by stress relieving method using vacuum furnace. Hardness measurement was carried out using microhardness Vickers at 150 mN load and 15 s loading time. Compressive strength, plateau stress and energy absorption were calculated using a universal testing machine. Findings: It was found that the highest value of hardness of 192.78 Hv was obtained when the stress relieving process is set with the following parameters: heating (500°C); holding time (120 min) and stabilization temperature (450°C). Since higher heating temperature and longer holding time produce sample with larger grain size and has an adverse effect on the hardness value It was revealed that the mechanical properties of aluminium alloy foam were enhanced when the heating temperature was decreased, holding temperature was diminished and the stabilization temperature was increased. Overall, the presented results showed that the thermal processing parameters such as heating temperature, holding time and stabilization temperature have a significant influence on improving the mechanical properties of aluminium alloy foam. Research limitations/implications: The properties of closed-cell aluminium alloy foam are highly sensitive and depend on the post heat treatment process. The processing parameters should be controlled in order to manipulate the properties of closed-cell aluminium alloy foam. Originality/value: To investigate the influences of these processing parameters on the physical and mechanical properties of the closed-cell aluminium alloy foam.

Preparation of Large-Diameter Semi-Solid 7075 Aluminum Alloy Billets

2008 ◽  
Vol 141-143 ◽  
pp. 361-365 ◽  
Author(s):  
Wei Wei Wang ◽  
Jian Li Song ◽  
Shou Jing Luo
Keyword(s):  
Aluminum Alloy ◽  
Heating Temperature ◽  
Large Diameter ◽  
Processing Parameters ◽  
7075 Aluminum Alloy ◽  
Dimensional Precision ◽  
Average Grain Size ◽  
Wide Range ◽  
Fine Microstructure ◽  
Semi Solid

Preparation of semi-solid microstructure of 7075 aluminum alloy industrial extrusion billets was studied in this paper. A new semi-solid microstructure preparation process is proposed. In the treatment, melting-stirring and predeformation of the alloy billets are not required. An ideal microstructure and higher dimensional precision of the billet can be obtained only with a direct heating and insulation method. The influences of different heating temperatures and insulation time on the microstructure evolution were studied with orthogonal testing methods. The obtained microstructure was observed and analyzed by optical microscopy, and the formation mechanism of the semi-solid microstructure is further discussed. The results indicate that a fine microstructure can be obtained with the proposed process and the processing parameters can be controlled over a wide range. Also, the grain microstructure obtained by the present process is better than that of the SIMA. For 7075 aluminum alloy billets, perfect fine equiaxial grains can be obtained under a heating temperature of 620°C and a holding time of about 25 minutes. The average grain size is around 80μm.

Development of a conical anode Fe-gun for low voltage SEM

1988 ◽  
Vol 46 ◽  
pp. 978-979
Author(s):  
T. Miyokawa ◽  
S. Norioka ◽  
S. Goto
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Low Voltage ◽  
Irradiation Damage ◽  
Cold Cathode ◽  
Virtual Source ◽  
Source Position ◽  
Electrostatic Lens ◽  
Electrostatic Lenses ◽  
Wide Range

Field emission SEMs (FE-SEMs) are becoming popular due to their high resolution needs. In the field of semiconductor product, it is demanded to use the low accelerating voltage FE-SEM to avoid the electron irradiation damage and the electron charging up on samples. However the accelerating voltage of usual SEM with FE-gun is limited until 1 kV, which is not enough small for the present demands, because the virtual source goes far from the tip in lower accelerating voltages. This virtual source position depends on the shape of the electrostatic lens. So, we investigated several types of electrostatic lenses to be applicable to the lower accelerating voltage. In the result, it is found a field emission gun with a conical anode is effectively applied for a wide range of low accelerating voltages.A field emission gun usually consists of a field emission tip (cold cathode) and the Butler type electrostatic lens.

AMPCOLOY 570

Alloy Digest ◽  
1980 ◽  
Vol 29 (3) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Cast Iron ◽  
Iron Alloy ◽  
Heat Treating ◽  
Nickel Aluminum ◽  
High Quality ◽  
Glass Making ◽  
Temperature Performance ◽  
Wide Range ◽  
Cobalt Iron

Abstract AMPCOLOY 570 is a cast copper-nickel-aluminum-cobalt-iron alloy specially developed for applications involving severe stresses and high temperatures, such as glass-making molds and plate-glass rolls. It is significantly superior to cast iron which has been commonly used for glass-making molds. Good foundry techniques will yield high-quality castings of Ampcoloy 570 in a wide range of section sizes. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Cu-392. Producer or source: Ampco Metal Inc..

A multi-shop integrated scheduling algorithm with fixed output constraint

2021 ◽  
pp. 1-9
Author(s):  
Yingchun Xia ◽  
Zhiqiang Xie ◽  
Yu Xin ◽  
Xiaowei Zhang
Keyword(s):  
Constraint Programming ◽  
Programming Model ◽  
Scheduling Algorithm ◽  
Processing Parameters ◽  
Scheduling Problem ◽  
Integrated Scheduling ◽  
Scheduling Scheme ◽  
Wide Range ◽  
Constraint Programming Model ◽  
Output Constraint

The customized products such as electromechanical prototype products are a type of product with research and trial manufacturing characteristics. The BOM structures and processing parameters of the products vary greatly, making it difficult for a single shop to meet such a wide range of processing parameters. For the dynamic and fuzzy manufacturing characteristics of the products, not only the coordinated transport time of multiple shops but also the fact that the product has a designated output shop should be considered. In order to solve such Multi-shop Integrated Scheduling Problem with Fixed Output Constraint (MISP-FOC), a constraint programming model is developed to minimize the total tardiness, and then a Multi-shop Integrated Scheduling Algorithm (MISA) based on EGA (Enhanced Genetic Algorithm) and B&B (Branch and Bound) is proposed. MISA is a hybrid optimization method and consists of four parts. Firstly, to deal with the dynamic and fuzzy manufacturing characteristics, the dynamic production process is transformed into a series of time-continuous static scheduling problem according to the proposed dynamic rescheduling mechanism. Secondly, the pre-scheduling scheme is generated by the EGA at each event moment. Thirdly, the jobs in the pre-scheduling scheme are divided into three parts, namely, dispatched jobs, jobs to be dispatched, and jobs available for rescheduling, and at last, the B&B method is used to optimize the jobs available for rescheduling by utilizing the period when the dispatched jobs are in execution. Google OR-Tools is used to verify the proposed constraint programming model, and the experiment results show that the proposed algorithm is effective and feasible.

LOW-NOISE SILICON-ON-INSULATOR HALL DEVICES

2004 ◽  
Vol 04 (02) ◽  
pp. L345-L354 ◽  
Author(s):  
Y. HADDAB ◽  
V. MOSSER ◽  
M. LYSOWEC ◽  
J. SUSKI ◽  
L. DEMEUS ◽  
...  
Keyword(s):  
Noise Level ◽  
Low Voltage ◽  
Silicon Layer ◽  
Electrical Current ◽  
Low Noise ◽  
Silicon On Insulator ◽  
Technological Parameters ◽  
Wide Range ◽  
Hall Sensors ◽  
Soi Technology

Hall sensors are used in a very wide range of applications. A very demanding one is electrical current measurement for metering purposes. In addition to high precision and stability, a sufficiently low noise level is required. Cost reduction through sensor integration with low-voltage/low-power electronics is also desirable. The purpose of this work is to investigate the possible use of SOI (Silicon On Insulator) technology for this integration. We have fabricated SOI Hall devices exploring the useful range of silicon layer thickness and doping level. We show that noise is influenced by the presence of LOCOS and p-n depletion zones near the edges of the active zones of the devices. A proper choice of SOI technological parameters and process flow leads to up to 18 dB reduction in Hall sensor noise level. This result can be extended to many categories of devices fabricated using SOI technology.

Sign in / Sign up

Export Citation Format

Share Document