Novel foaming agent used in preparation process of aluminum foams

The performances of a novel foaming agent used in the preparation process of aluminum foams were investigated, and the effects of some factors, such as addition of the foaming agent, foaming temperature on the porosity, and appearance of aluminum foams were also discussed. Experimental results show that the novel foaming agent has a wide decomposition temperature range and a mild decomposed rate; the foaming agent has the ability to enhance the viscosity of aluminum melt, as a result, an extra viscosifier such as Ca or SiCp is unnecessary while using this foaming agent; the bubble-free zone in material decreases and the foaming effi- ciency increases with the increase of foaming agent; the bubble-free zone disappears and the foaming efficiency is near 100% when the addition of foaming agent is more than 1.4wt%; the porosity of the aluminum foam increases with the increase of foaming agent when the addition of foaming agent is less than 2.2wt%.

Experimental assessments of methanol-based foaming agent in latex modified foamed binders and warm asphalt mixtures

Latex is one of the natural rubbers that is used to enhance the performance of asphalt pavement for the last few decades.The presence of latex,which is categorized as an elastomer,helps to improve pavement performance and durability.Conversely,higher viscosity of latex modified asphalt binder increases the production-temperatures of asphalt mixture,thus consuming higher energy during asphalt mixture’s production stage.In this study,the effectiveness of methanol as an energy-efficient foaming agent was assessed to reduce the viscosity and enhance the workability of the modified asphalt binder.The basic and rheological properties of the asphalt binders were determined through multiple laboratory tests including expansion ratio and half-life,rotational viscosity,softening point,torsional recovery,and dynamic shear rheometer.The properties of asphalt mixtures were assessed through the service characteristics,mechanical performance,and moisture resistance criteria.It was found that the presence of latex results in an approximately twofold higher expansion ratio and a lower half-life of the asphalt binder at about the same ratio.Through the rotational viscosity test,the application of methanol into asphalt binder decreased the viscosity and led to better workability,despite the addition of latex as an asphalt modifier.The application of methanol into asphalt binder improved the workability of mixture samples and lowered the compaction energy of the compaction process,which are the crucial criteria for a better mixing and compaction process.Methanol foamed asphalt mixtures with latex show much higher resistance to moisture damage and stiffness than control sample even though they were prepared at a lower temperature.

Carbonates as Foaming Agent in Chip-based Aluminium Foam Precursor

Replacement of TiH2 as foaming agent by CaCO3（lime） and CaMg（CO3）2（dolomite） for AlMg4.5-and AlSi9Cu3-foams was investigated considering inluences on foaming capability and cellular structure.Precursor materials were produced from alloy chip and powder mixtures by means of the thixocasting process.AlSi9Cu3 variants showed expansion levels suffcient for commercial use.Variations in expansion observed when CaCO3 and CaMg（CO3）2 were compared as foaming agent are explained based on the course of decomposition.Improved performance of dolomite-based foams relies on formation of stabilizing MgO phases,which do not develop during decomposition of CaCO3 in Al-Si-Cu alloys

Effect of foaming agent,foam stabilizer and whipping time on drying process of tomato paste under different drying equipment

Laboratory experiments were conducted to determine the effect of foaming agent(egg white(EW)),foam stabilizer(carboxyl methyl cellulose(CMC))and whipping time on drying rate and quality of tomato(Lycopersicon esculentus)paste dried under air oven,microwave oven and mechanical dryer.A 43 factorial experiment in Randomized Complete Block Design(RCBD)was used to study the effect of four levels each of foaming agent(5%,10%,15%and 20%EW),foam stabilizer(0.15%,0.30%,0.45%and 0.60%CMC)and whipping time(3,5,7 and 9 min)on the drying rate and the quality of foam-mat dried tomato powder in the three drying equipment.Each trial was performed in triplicates making a total number of 576 samples that were individually tested and measured.25 g sample of the paste was dried to a moisture content of 7.60%(wb)for 8 h in mechanical dryer and oven dryer at temperatures of 55◦C and 50◦C,respectively,and 10 min in microwave oven at 540 W.Data obtained from the experiments were statistically analyzed using the analysis of variance(ANOVA)while the Duncan’s Multiple Range Test was used to compare the means.Results showed that the drying rate increased with increase in foaming agent,foam stabilizer and whipping with minimum values of 9.21 g/h obtained in mechanical dryer,9.31 g/h in air oven and 8.05 g/h in microwave oven.Increase in foaming agent,foam stabilizer and whipping time did not cause any adverse effect on vitamin C,ash,protein,fat,carbohydrate,crude fiber contents of the samples.Samples reached a stable moisture content of 7.60%(wb)in less than 8 h in mechanical dryer and air and less than 10 min in microwave oven.The results of the study showed that EW,CMC and whipping time influenced the drying rate and quality of foam-mat dried tomato powder.

Effects of foaming parameters on microstructure and compressive properties of aluminum foams produced by powder metallurgy method

Semi open-cell aluminum foams having channels between individual cells were produced using low cost CaCO3foamingagent and applying the powder compact melting process.To this end,the aluminum and CaCO3powder mixtures were coldcompacted into dense cylindrical precursors for foaming at specific temperatures under air atmosphere.The effects of severalparameters including precursor compaction pressure,foaming agent content as well as temperature and time of the foaming processon the cell microstructure,linear expansion,relative density and compressive properties were investigated.A uniform distribution ofcells with sizes less than100μm,which form semi open-cell structures with relative densities in the range of55.4%-84.4%,wasobtained.The elevation of compaction pressure between127-318MPa and blowing agent up to15%(mass fraction)led to anincrease in the linear expansion,compressive strength and densification strain.By varying the foaming temperature from800to1000°C,all of the investigated parameters increased except compressive strength and relative density.The results indicated theoptimal foaming temperature and time as900°C and10-25min,respectively.

Preparation of Controllable Cross-Linking Polyethylene Foaming Materials and Their Properties

In order to prepare the polyethylene materials with controlling properties,we developed two kinds of controllable cross-linking polyethylene foaming system.2,5-dimethyl-2,5-bis (tert-butyl peroxy) hexane was used as cross-linking agent and TEMPO as cross-linking inhibitor,azodicarbonamide (AC) was used as foaming agent and citric acid as foaming promoter.The density,expansion ratio,cellular structure and mechanical property of these two kinds of controllable materials were studied.Experimental results show that,properties of these two kinds of materials appear similar trend:cellular size and expansion ratio are enlarged with the amount of cross-linking inhibitor or foaming promoter increasing,while density and mechanical strength appear decreasing trend.Through comparing those two material systems’ properties,cross-linking polyethelene foaming system with citric acid as foaming promoter has better properties.

High Efficiency Dust Scrubbers for Continuous Miner in Underground Mines

Based on the experimental data by a full scale test model and the relevant existing achievements, four new concepts of group dust scrubbers were designed in the paper. The new dust scrubbers consist of two to four common dust separators in series: wet fan, wet Venturi and foam filter bed. Wetting and foaming agents are used to increase the efficiency of dust separation. High efficiency is not required for each part of the group dust scrubbers, but the whole system has a high working reliability. All parts of the group dust scrubbers have the most suitable separating efficiency for different size and concentration of dust particles in airflow, according to their technical features. Four group dust scrubbers have a high efficiency from 94.4% to 99.7% for separating respirable dust at a rational cost.

Application of foam technology for dust control in underground coal mine

In order to effectively control the dust in the underground coal mine,this study proposes and develops a new technology for dust control by foam,and briefly demonstrates the advantage of the foam technology for dust control,such as the good isolation performance,large contact area,high wetting ability,strong adhesion and so on.Besides,the details of the technology are introduced,including the foam agent,foam generator,and foam production process.Then the paper studies the relationship between the foaming agent concentration and liquid surface tension,and explains the principle of the foam generator.The technology is applied in heading face.The application results show that the foam has a remarkable effect on dust control in underground coal mines.

Preparation and Properties of Alkali Activated Foam Cement Reinforced with Polypropylene Fibers

A new form of foam cement was produced by mixing alkali-activated slag,clay,a small amount of polypropylene fibers with prepared foam during stirring.The preparation of the material is quite different from the normal one,which is produced just at room temperature and without baking.The fabrication of this energy-saving and low-price material can be favorable for lowering carbon emission by using recycled industrial wastes.Thermal conductivity of 0.116 W/（m·k）,compressive strength of 3.30 MPa,flexural strength of 0.8 MPa and density of 453 kg/m3 can be achieved after 28 days aging.The hydration product is C-S-H with less Ca（OH）2,calcium aluminum and zeolite,which was characterized by X-ray diffraction（XRD） measurement.This prospective foam cement may be expected to be an excellent economical energy-saving building material.

Design-Oriented Thermodynamic Analysis of Novel Heat-Integrated C5 Isomeride Distillation Scheme on Pilot Scale

A novel heat-integrated distillation scheme on pilot scale for producing C5 foaming agent, a mixture of isopentane and pentane in a certain proportion, was proposed with the aid of process simulation. Compared with the conventional distillation scheme, C5 foaming agent was directly separated at the top of the original isopentane or pentane column in the novel scheme, instead of first refining the two isomerides to high purities and then mixing them into final products. This improvement reduced the difficulty of the separation and avoided meaningless exergy loss caused by re-mixing, which finally contributed to an energy-efficient design by a big margin. Moreover, the column grand composite curves(CGCCs)were used to modify all distillation columns, indicating that there is potential to improve the energy efficiency further. Therefore, double-effect, or heat-integrated distillation was also adopted. Energy and exergy analyses were then conducted to evaluate the effectiveness of the proposed scheme for the purpose of energy saving. The simulation results of the conventional distillation scheme were in agreement with its on-site counterpart. Analyses showed that the novel heat-integrated scheme reduced hot utility by 27.12%,, cold utility by 24.49%,, and total exergy loss by 23.95%,.

Models for Predicting the Jet Trajectory and Intensity Drop Point of Fire Monitors

Two models are defined for predicting the trajectory of a foam jet originating from a fire monitor(hydrant)and the related intensity drop point.An experimental framework is also defined and used accordingly to compare real-time data with the predictions of such models.This mixed theoretical-experimental approach is proven to be effective for the determination of otherwise unknown coefficients which take into account several important factors such as the operation pressure,the elevation angle and the nozzle diameter.It is shown that the mean absolute error is smaller than 20%.

Properties and effect of forming sewage sludge into lightweight ceramics

In this work we investigated the chemical, thermal and toxic properties of dried sewage sludge （DSS）, the preparation and properties of lightweight sludge ceramic （LSC） and the mechanisms of action of the organic and inorganic foaming agents （OFAs and IFAs）. The chemical components and thermal properties of the raw materials were studied by Energy Dispersive X-ray Detection （EDX） and Thermogravimetric Analysis and Differential Scanning Calorimetry （DSC/TGA）. The mineral phases of the raw materials and the formed ceramics were determined by X-ray Diffraction （XRD）. The leaching characteristics of heavy metals were investigated with inductively Coupled Plasma Atomic Emission Spectrometry （ICP-AES）. Different ratios of DSS and clay were mixed and pressed into raw pellets. After drying and preheating treatment, the raw pellets were sintered at 1150℃ for 10 rain. The physical properties of LSC （50 wt% DSS added） were tested. The results showed that when the addition of DSS was above 50 wt%, LSC began to shrink, and a maximum density occurred. The environmental safety of LSC was satisfactory. XRD showed that some new mineral phases formed in the LSC. Observation of the microstructure by Scanning Electron Microscope （SEM） indicated that the body of LSC was porous.

Ethanol based foamed asphalt as potential alternative for low emission asphalt technology

Foamed asphalt typically relies on water as a foaming agent because water becomes gaseous at elevated temperatures, generating numerous tiny bubbles in the asphalt and causing spontaneous foaming. In this study, ethanol was used as a potential alternative to water as a foaming agent. Ethanol is expected to be a physical blowing agent in the same manner as water, except it requires less energy to foam due to its 78 ℃ boiling point. This study compares the performance of water and ethanol as foaming agents through the measurements of rotational viscosity, the reduction in temperature during foaming, and volatile loss. The ethanol-foamed asphalt binders were prepared at 80 ~C and 100 ~C, while the water-foamed asphalt binders were prepared at 100 ~C and 120 ~＇C. Additionally, the rolling thin film oven （RTFO） was used to generate short-term aging of the foamed asphalt binders. A rotational viscometer was used to determine the viscosity of the asphalt binders at 80 ~C, 100 ~C, 120 ~C, 140 ~C, and 160 ~C. Overall, ethanol can function in the same manner as water but requires less energy to foam. It is proven based on the smaller drop in temperature of the asphalt binder foamed using ethanol compared with that prepared with water. This is due to the lower latent heat capacity of ethanol, which requires less energy to vaporize compared with water. Through the rotational viscometer test, ethanol performs better in lowering the viscosity of asphalt binders, which is essential in allowing produc- tion processes at low temperatures, as well as a better workability and aggregate coating. Ethanol can be expelled from the foamed asphalt binders at a higher rate due to its lower boiling point and latent heat.