scholarly journals Effect of W on the Impact-Induced Energy Release Behavior of Al–Ni Energetic Structural Materials

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1217
Author(s):  
Shun Li ◽  
Caimin Huang ◽  
Jin Chen ◽  
Yu Tang ◽  
Shuxin Bai
Keyword(s):  
Energy Release ◽  
Structural Materials ◽  
Damage Effect ◽  
Hot Press ◽  
Reaction Heat ◽  
Metal Metal ◽  
Energetic Structural Materials ◽  
Released Energy ◽  
The Impact ◽  
Hot Press Process

Energetic structural materials (ESMs) are an important class of military materials due to their good structural and energy-releasing characteristics. To improve the damage effect of metal–metal ESMs with good mechanical properties, W was added to the 48Al–52Ni composites, and the effect of W on the impact-induced energy release behaviors was investigated. The results showed that the hot-press process and the addition of W did not change the microstructure and surface state of the constituent particles, leading to a stable onset temperature of the Al–Ni intermetallic reaction in (48Al–52Ni)100-xWx composites. Meanwhile, the decrease in the contact area between Al and Ni in the composites with increased W content resulted in the decrease in reaction heat. During the impact process, the intermetallic reaction of W caused by the Al–Ni intermetallic reaction, as well as the oxidation reaction of Al and Ni caused by the brittle fracture along the weak interface, caused the released energy of (48Al–52Ni)40W60 to reach 2.04 kJ/g.

Predicting of atmospheric corrosivity and durability of structural materials. Part II. Impact of urban traffic pollution

2021 ◽  
Vol 26 (2) ◽  
pp. 25-33
Author(s):  
Joanna Kobus ◽  
Rafał Lutze
Keyword(s):  
Zinc Coating ◽  
Environmental Parameters ◽  
Structural Materials ◽  
Traffic Volume ◽  
Urban Traffic ◽  
Traffic Pollution ◽  
Street Traffic ◽  
The Impact

The results of the atmospheric corrosivity assessment in the immediate vicinity of streets of different traffic volume in Warsaw, Krakow and Katowice are derived . On the bases of annual exposures in 2014–2018 years an equation describing the impact of environmental parameters and street traffic volume on corrosion losses of zinc and zinc coating on steel was selected.

Coupling Numerical Simulation of Resin Matrix Composites about Temperature and Degree of Cure Fields by Hot-Press Forming

2013 ◽  
Vol 788 ◽  
pp. 43-47
Author(s):  
Fei Sun ◽  
Dun Ming Liao ◽  
Peng Xu ◽  
Chang Chun Dong
Keyword(s):  
Three Dimensional ◽  
Exothermic Peak ◽  
Resin Matrix ◽  
Transient Temperature ◽  
Heating Process ◽  
Curing Process ◽  
Hot Press ◽  
Degree Of Cure ◽  
Resin Matrix Composite ◽  
The Impact

In this paper, a coupled numerical model of three-dimensional transient temperature field and degree of cure field for resin matrix composite curing process was developed. Using this model the hot-press curing process of the plate-shaped composite parts were simulated with considering the impact of tools and auxiliary materials. Thus, the temperature and degree of cure fields distribution in the entire process cycle were obtained. Numerical results show that the curing of the composite has a certain sequence. At the beginning, the composite is first curing at the boundary and gradually to the center. At the end stage, because of the higher curing rate, the center released a large amount of heat which makes the boundary curing simultaneously with center. In addition, there is a significant exothermic peak during the curing process. And the peak temperature is higher when it was closer to the center. This research effectively provides reference for optimizing the heating process parameters to improve product quality.

scholarly journals Experimental characterisation of the thermal energy released by a Radio-Frequency Corona Igniter in Nitrogen and Air

2020 ◽  
Author(s):  
Gabriele Discepoli
Keyword(s):  
Radio Frequency ◽  
Thermal Energy ◽  
Surrounding Medium ◽  
Energetic Efficiency ◽  
Driving Voltage ◽  
Pure Nitrogen ◽  
Ignition System ◽  
Application Range ◽  
Released Energy ◽  
The Impact

The Radio-Frequency Corona Ignition System is characterised by a wide initial combustion volume and precursors production, via radical insemination by the streamers, in addition to high released thermal energy. These features lead to faster combustion, a higher tolerance for lean mixtures and EGR dilutions and, in general, more adaptability. The thermal energy released by the igniter to the surrounding medium can help to understand the performance, the behaviour and the application range. This paper proposes a systematic experimental analysis of the thermal energy released by the igniter at room temperature, via pressure-based calorimetry. This analysis, carried out at different pressures (up to 10 bar) and medium type (air or nitrogen), is extended to the whole range of the corona igniter control parameters, namely streamer duration and driving voltage. The latter is proportional to the maximum electrode voltage, as shown in the model here presented, and as confirmed by experiments. The results show, for all the vessel pressures, the high energetic efficiency of the ignition system and the high amount of the released energy. The latter is found to increase linearly with the corona streamers duration and quickly with the driving voltage up to the streamer-to-arc transition threshold. The efficiency tends to reach a defined upper limit. For each tested point, the energy released to pure nitrogen is higher than to air, which evidences the impact of the oxygen presence under streamer exposure.

Effect of calcite addition on technical properties and reduction of formaldehyde emissions of medium density fiberboard

BioResources ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. 3718-3733
Author(s):  
Osman Camlibel
Keyword(s):  
Liquid Paraffin ◽  
Urea Formaldehyde ◽  
Medium Density Fiberboard ◽  
Formaldehyde Emission ◽  
Modulus Of Rupture ◽  
Medium Density ◽  
Wood Fibers ◽  
Hot Press ◽  
Ammonium Sulphate Solution ◽  
Hot Press Process

Physical, mechanical, and formaldehyde emission properties were studied for medium density fiberboard (MDF) produced with oak (75%) and pine (25%) fibers that had been mechanically refined in the presence of calcite particles. The calcite slurry was prepared at two levels of solids, 1.5% and 3% (10 and 20 kg·m-³). Chips were cooked for 4 min at 185 °C, under 8 bar vapor pressure in an Andritz defibrillator. 1.8% liquid paraffin, 0.72% ammonium sulphate solution, and 11% urea-formaldehyde were added by percentage based on oven-dried wood fibers in the blowline at the exit of the defibrator. The fibers were dried to 11% moisture content. MDF boards (2100 mm × 2800 mm × 18 mm) were created using a continuous hot-press process. The addition of calcite in the course of MDF production resulted in improved physical properties, such as thickness swelling (ThS 24 hours) and water absorption (WA 24 hours). MDF boards prepared with calcite exhibited higher internal bond (IB), modulus of rupture (MOR), and modulus of elasticity (MOE). Resistance to axial withdrawal of screw also was increased by addition of 3% calcite. In addition, the lowest levels of formaldehyde emission were observed for MDF prepared with calcite at the 3% level.

scholarly journals Influence of Incorporation of Natural Fibers on the Physical, Mechanical, and Thermal Properties of Composites LDPE-Al Reinforced with Fique Fibers

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Miguel A. Hidalgo-Salazar ◽  
Mario F. Muñoz ◽  
José H. Mina
Keyword(s):  
Natural Fibers ◽  
Mechanical And Thermal Properties ◽  
Hot Press ◽  
Scanning Calorimetry ◽  
Aluminum Particles ◽  
Direct Function ◽  
Tetra Pak ◽  
Fique Fibers ◽  
The Impact ◽  
Properties Of Composites

This study shows the effect of the incorporation of natural fique fibers in a matrix formed by low-density polyethylene and aluminum (LDPE-Al) obtained in the recycling process of long-life Tetra Pak packaging. The reinforcement content was 10, 20, and 30% fibers, manufactured by hot-press compression molding of composite boards (LDPE-Al/fique). From the thermogravimetric analysis (TGA) it was determined that the proportions of the LDPE-Al were 75 : 25 w/w. Likewise, it was found that the aluminum particles increased the rigidity of the LDPE-Al, reducing the impact strength compared to LDPE recycled from Tetra Pak without aluminum; besides this, the crystallinity in the LDPE-Al increased with the presence of aluminum, which was observed by differential scanning calorimetry (DSC). The maximum strength and Young’s modulus to tensile and flexural properties increased with the incorporation of the fibers, this increase being a direct function of the amount of reinforcement contained in the material. Finally, a reduction in the density of the compound by the generation of voids at the interface between the LDPE-Al and fique fibers was identified, and there was also a greater water absorption due to weak interphase fiber-matrix and the hydrophilic fibers contained in the material.

A Patch-Type Flexible Physiological Monitor on a Non-Woven Material

2006 ◽  
Vol 969 ◽  
Author(s):  
Wen-Yang Chang ◽  
Jin-Sheng Chang ◽  
Chun-Hsun Chu ◽  
Tzong-Che Ho ◽  
Yu-Cheng Lin
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
The Body ◽  
Hot Press ◽  
Postural Change ◽  
Good Adhesion ◽  
Patch Type ◽  
Speed Up ◽  
Trace Line ◽  
Hot Press Process

AbstractThe study reported is about an integrated wireless physiological monitor module of the flexible patch type, used on a non-woven material to package this module by a hot press process. The module can monitor the body temperature and heart rate. Experimental results showed that the specification and accuracy should be 25-40 °C ± 0.5 °C and 50-200 bpm ± 2 bpm. The main advantage of the module is that the postural change can be monitored. At the same time, it has also a good adhesion between substrate and components, without crack of conductor trace line after bending the module repeatedly. Thickness is about 2 mm. The aim of this study is to speed up the physiological technology and to create more efficiency by miniaturization. In addition, the acceptance level of wearing it is increased by the small and ergonomic design.

scholarly journals Experimental Study on the Effect of Advancing Speed and Stoping Time on the Energy Release of Overburden in an Upward Mining Coal Working Face with a Hard Roof

2019 ◽  
Vol 12 (1) ◽  
pp. 37 ◽  
Author(s):  
Feng Cui ◽  
Yanbin Yang ◽  
Xingping Lai ◽  
Chong Jia ◽  
Pengfei Shan
Keyword(s):  
Coal Seam ◽  
Energy Release ◽  
Rock Burst ◽  
Response Ratio ◽  
Working Face ◽  
Significant Difference ◽  
Loading And Unloading ◽  
Microseismic Events ◽  
Microseismic Event ◽  
The Impact

In order to study the influence of advancing speed and stoping time of a coal face on the scale and frequency of rock burst, the energy release characteristics of an overburden fracture under six advancing speeds and four stoping times are studied by theoretical analysis and similar simulation experiments. The distribution characteristics of microseismic events before and after stoppage are compared, and the load/unload response ratio is introduced to analyze the relationship between the synergistic effect of advancing speed and stoping time and the characteristics of microseismic events in coal and rock mass. The mechanism of rock burst induced by the advancing speed and stoping time effect in the working face is studied, and the coordinated regulation and mitigation of advancing speed and stoping time are analyzed and completed. The results show that the effect of advancement speed and stoping time is very important to the energy release of overburden. The energy released by microseismic events during stoping is exponentially related to the advancing speed. The change of advancing speed causes the change of microseismic event characteristics, reflecting the evolution process of overburden structure and its energy. During stoping, the secondary microseismic events disturbed by mining occur frequently, leading to the significant difference of energy released by microseismic events during stoping. After stoping, the microseismic energy is more than four times higher than that during the stop period, and the risk of coal seam impact is high during the stope period. The synergetic change of advancement speed and stoping time changes the cycle of energy accumulation and release. The response ratio of loading and unloading considering the effect of advancement speed and stoping time is established by using the corresponding ratio of loading and unloading, and the impact risk of the coal seam is quantitatively analyzed. Based on the monitoring and analysis of microseismic events, the safety mining index of coordinated control with the energy of a single microseismic event of 180 J is established, and the best advancing speed of the working face is determined to be 4 m/d. According to the corresponding ratio of loading and unloading, the reasonable stoping time of different advancing speeds and the corresponding advancing speed of different stoping times after the resumption of mining are determined, so as to provide a reference for the safe and efficient mining of similar rock burst mines.

scholarly journals Research on the Energy Release Characteristics of Six Kinds of Reactive Materials

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3940 ◽  
Author(s):  
Xianwen Ran ◽  
Liangliang Ding ◽  
Jingyuan Zhou ◽  
Wenhui Tang
Keyword(s):  
Energy Release ◽  
The Self ◽  
Weight System ◽  
Test Device ◽  
Reactive Material ◽  
Reactive Materials ◽  
Release Test ◽  
Penetration Ability ◽  
Speed Up ◽  
The Impact

Currently, PTFE/Al is widely used in the reactive fragmentation warhead. However, for the same explosive yield, the reactive fragments usually have a smaller damage-radius than the inert fragments because PTFE/Al has a poor penetration ability and needs an impact-speed up to 1000 m/s to stimulate its chemical reaction. To enhance the damage power of reactive fragments, six kinds of reactive materials (PTFE/Al, PTFE/B, PTFE/Si, PTFE/Al/B, PTFE/Al/Si, and PTFE/Al/CuO) based on PTFE were designed and studied. Through the drop weight system and the self-designed energy release test device, qualitative and quantitative analysis of the energy release ability of six kinds of reactive materials were carried out. The qualitative analysis results indicate that the reactions of PTFE/B and PTFE/Si are weak under the impact of drop hammer with only a very weak fire light produced, while the reactions of PTFE/Al, PTFE/Al/B, PTFE/Al/Si, and PTFE/Al/CuO are relatively intense, and the reaction of PTFE/Al/Si is the most intense. Through the self-designed energy release test device, the energy release ability of the reactive material was quantitatively compared and analyzed. The results show that the energy release ability of the four formulations were as follows: PTFE/Al/Si > PTFE/Al/CuO > PTFE/Al/B > PTFE/Al. Therefore, it can be concluded that the PTFE/Al/Si formulation is a new reactive material with strong energy release ability, which can be a new choice for reactive fragment.

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