Exothermic Agent Research Articles

Study on the Properties of Chemical Foaming Injection Molded Polyolefin/Chitosan Composites

Chitosan is a biodegradable material with good biocompatibility. It can be used in medicine, foodstuff, the chemical industry and heavy metal adsorption. In this study, an exothermic foaming agent (Azodicarbonamide) injection molded was added to polypropylene (PP), maleic anhydride (MA) grafted PP (PPgMA) and Chitosan composites. MA served as a compatibilizer due to the poor bonding between PP and chitosan. This study investigated the effects of the modifier and chitosan loading on the tensile strength, thermal properties and morphology in chemical foam injection-molded PP and PPgMA composites. The results showed that the tensile strength decreased with the addition of chitosan, but Young’s modulus increased with the added chitosan loading. The enhancement was significant for foam injection molding. The cell size decreased and the cell density increased with the addition of chitosan for the PP/PPgMA composites. The thermogravimetric analysis (TGA) results showed that the thermal degradation could be decreased with the addition of chitosan in both the PP and PPgMA composites. The use of foamed chitosan composites will be further investigated in the removal of heavy metal in waste water.

A Static Balance Model and Analysis of 430 Stainless Steel Produced by Basic Oxygen Furnace–Argon Oxygen Decarburization Furnace Process

Herein, a static mass and energy balance model of 430 stainless steel (SS) produced by the basic oxygen furnace (BOF)–argon oxygen decarburization furnace (AOD) process is established and verified by plant data. It is found that in the AOD, the energy input is efficiently utilized, the heat available for other uses is relatively low (4.0%), and the addition of SS scrap is limited. The high carbon content of dephosphorization hot metal (DPHM) and post‐combustion ratio (PCR) in AOD are conducive to promoting the recycling of SS scrap. In contrast, when the carbon content of DPHM and PCR is low, it is necessary to add an exothermic agent to the furnace. Due to the saving of nickel‐containing raw materials and China's high proportion of thermal power, the carbon emissions and energy consumption per ton 430 SS produced by the BOF–AOD process are 3131 kg‐CO2 and 24 161 MJ, which is much lower than per ton 304 SS produced by the electric arc furnace (EAF)–AOD process. Meaning the former is more conducive to the promotion of energy conservation and emission reduction.

J0330201 化学反応を利用した無機多孔体の合成プロセスと用途展開

Porous metals, which contain large amount of pores inside, exhibit various unique physical and mechanical properties, such as low bulk density and high strain energy absorbing capability. In this presentation, a novel processing method (reactive precursor method) to synthesize high-melting point porous metals and an attempt to control the cell structure are discussed. A precursor is made by blending two or more kinds of elemental powders. The precursor is then heated to ignite an exothermic reaction between the elemental powders. The closed-cell porous structure is obtained when the maximum temperature during the reaction exceeds the melting point of the reaction product, and open-cell porous structure is obtained when the maximum temperature is below the melting point. Therefore, if the optimum porous structure is the closed cell, then an additive powder (exothermic agent powder) which releases large amount of heat of reaction should be additionally blended. By blending additive powders in the precursor, the maximum temperature can be controlled. Aside from the additive powders, replication powders are also used to extend the diversity of cell morphology. Closed, flat, open, bimodal-sized and high-porosity open pores are currently achieved by the reactive precursor process.

Morphological Control of Porous Structure in Al-Ti Intermetallics Foam Manufactured by Reactive Precursor Process

In this paper, a novel processing method (reactive precursor method) to manufacture high-melting point porous Al-Ti intermetallics is investigated. Especially, morphological control of porous structure is focused. In the reactive precursor process, precursors are made by blending aluminum and titanium powders. The precursor is heated to ignite an exothermic reaction (so called “combustion reaction”) between the elemental powders. Pore formation is a well-known intrinsic feature of the combustion reaction, and we tried to control the pore morphology. Fundamentally, the closed-cell structure can be obtained when the maximum temperature during the reaction exceeds the melting point of the reaction product. By blending the exothermic agent powder in the precursor, the maximum temperature is increased and the reaction products are melted. The porosity is controlled by the maximum temperature. In contrast, an open-cell porous structure can be obtained when the maximum temperature is below the melting point of the reaction product. Microwave heating turned out to be an effective method to create an open cell structure. A powdery substance that does not react with other elemental powders (heat-absorbing agent powder) decreases the temperature during the reaction. Closed, open and bimodal-sized open pores have been achieved by the reactive precursor process so far.

Combustion Foaming of Al-Ti Intermetallics Studied In situ by Fast X-ray Radioscopy

Combustion foaming of Al-Ti intermetallics was observed in-situ by X-ray radioscopy at the Technical University Berlin, Germany, and at the experimental station ID-19 of the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. The acquisition rates were 6.7 fps and up to 500 fps, respectively. This allowed for observing in detail the internal structure development during combustion foaming of extruded Al-Ti powder compacts made with Al/Ti molar ratios of 3, 4 and 7 and containing 10 and 20 vol.% exothermic agent (Ti + B4C). At the beginning of the foaming process, μm-sized pores were observed. Foam shrinkage and pore coarsening started immediately after the combustion process. Specimens made with an Al/Ti ratio = 7 showed pore coarsening and a longer solidification time. Specimens with 10 vol.% exothermic agent experienced less volume expansion and pore coarsening than specimens with 20 vol.% exothermic agent. The specimens with an Al/Ti ratio = 4 contained fewer micropores than the one with an Al/Ti ratio = 3.

Foaming behavior of long-scale Al–Ti intermetallic foam by SHS mode combustion reaction

Long-scale Al–Ti intermetallic foam was fabricated by self-propagating high-temperature synthesis (SHS) mode combustion reaction with the help of exothermic agent and preheating treatment. The effect of exothermic agent and preheating condition on the SHS mode combustion reaction foaming of the long-scale Al–Ti intermetallic foam was investigated. Maximum temperature of combustion reaction, reaction propagation speed and porosity of specimen were increased by increasing the amount of exothermic agent. A correspondence relation between the distribution of porosity and the distribution of the maximum temperature throughout the self propagation direction was indicated. Long-scale Al–Ti foam which had 60–70% porosity and uniformed porosity distribution was earned with 623 and 673 K homogenous preheating. It was due to the appearance of Al3Ti liquid phase throughout the observation point of the specimen during the combustion reaction by the preheating treatment.

Study on the Index of Metallurgical Coke Strength after Reaction

The blast furnace coke plays four roles as exothermic agent, reducer, carburizer and framework. The former three roles can be played by other fuels, but the role as framework still can’t be played by other fuels by now. In order to ensure its skeleton role, it must be sure that the coke has enough high-temperature strength. This research uses KSJ decarbonizing electric furnace, drum-I and high temperature compressive testing machine to furthest simulate the coke’s actual actions in the blast furnace. The research indicates that comparing with the reactivity and strength index after reaction of coke GB4000-1996, the blast furnace coke’s high temperature compressive strength under a certain temperature and a certain carbon loss rate can give a more comprehensive evaluation of the quality of coke.

Effect of elemental powder blending ratio on combustion foaming behavior of porous Al–Ti intermetallics and Al 3Ti/Al composites

Porous Al–Ti intermetallics and Al 3Ti/Al composites were fabricated by combustion foaming process. Fundamentally, aluminum and titanium powders were blended (Al/Ti mole blending ratios ranging from 0.33 to 10.0). Additionally, boron carbide (B 4C) powder was blended as exothermic agent since the heat of TiC and TiB 2 formation is much higher than those of Al–Ti intermetallics. The blended powder compact was heated to induce the combustion reaction. Isotropic closed pores were produced by this process. By adding 10 vol.% exothermic agent, the porosity exceeded 60% in a wide range of Al/Ti ratios (3.0–10.0). It was confirmed that high heat of reaction of exothermic agent assisted the complete conversion of aluminum and titanium powders to Al 3Ti.

A Self-Propagating Foaming Process of Porous Al-Ni Intermetallics Assisted by Combustion Reactions

The self-propagating foaming process of porous Al-Ni intermetallics was investigated. Aluminum and nickel powders were blended, and titanium and boron carbide powders were added as reactive exothermic agents. The blended powder was extruded to make a rod-shape precursor. Only one end of the rod precursor was heated to ignite the reaction. The reaction propagated spontaneously throughout the precursor. Pore formation took place at the same time as the reaction occurred. Adding the exothermic agent was effective to increase the porosity. Preheating the precursor before the ignition was also very effective to produce porous Al-Ni intermetallics with high porosity.

Synthesis of Porous Al<SUB>3</SUB>Ti/Al Composite and Effect of Precursor Processing Condition on Cell Morphology

Porous Al 3 Ti/Al composite was fabricated by a combustion foaming process, which makes use of exothermic reactions between titanium, aluminum and boron carbide powders. Boron carbide powder was used as an exothermic agent to increase the heat of reaction. Fundamental combustion foaming behavior and effects of processing parameters (Al/Ti blending ratio, addition of exothermic agent and powder compacting pressure) on the foaming behavior were investigated. Combustion foaming took place over temperature ranges between melting points of aluminum and Al 3 Ti. Exothermic agent addition turned out to be effective to increase the porosity of porous Al 3 Ti/Al composite. Relative density of the precursor was an important factor, which needed to be higher than a threshold level (0.67) to prevent extremely inhomogeneous pore morphology. By conducting hot extrusion to the precursor, both pore size and porosity were increased. As a result of compressive test, high plateau stress and absorbed energy were achieved by increasing Al/Ti mole blending ratio from 4.0 to 7.0.

Ash-Melting Process Utilizing Thermite Reaction between Chromium Electroplating Sludge and Aluminum Dross

The aim of this work is to evaluate the possible application of the thermite reaction to the melting process of the municipal solid waste incineration ash (MSWI ash). The thermite agent was produced by mixing calcined chromium electroplating sludge with aluminum dross in appropriate stoichiometric proportions and then forming the mix into variously sized balls. The effect of size of the ball on the amount of melted MSWI ash, aggregation of metallic substances in the slag, and the level of environmental safety of generated slag were investigated. The reaction was initiated by heating a mix of single thermite ball and MSWI ash in a muffle furnace, and generated molten slag. The amount of MSWI ash increased with the weight of the thermite balls linearly, and its ratio was from 2.0 to 2.4. Comparative elution tests of untreated MSWI ash, MSWI slag, and thermite-derived slag show the environmental benefits of this type of approach. This paper presents the feasibility of ash melting process with thermite agent, the maximum amount of MSWI ash melted by one thermite ball, and the environmental benefits. Mixing a thermite agent with MSWI ash as an exothermic agent enhances the efficiency of the melting process, alleviates the energy consumption, and can be used to conventional melting techniques.