Effect of Foaming Agent and Endothermic Agent Addition on Foaming Behavior of NiTi Alloy Made by Combustion Synthesis

Al2O3-TiO-TiO2 multiphase foam ceramic was prepared with Al powders and TiO2 powders by combustion synthesis, Direct observation and metallographic microscope indicated that the pore diameter is 100~6000μm, and Archimedean method showed that the porosity is 35~50%. The influencing factors of the pore diameter and porosity and, the effects of adding SiO2 on compression strength of the Al2O3- TiO-TiO2 multiphase foam ceramic were discussed. It was shown that the addition of proper high temperature foaming agent can increase porosity and adding SiO2 can decrease porosity. The Al2O3-TiO-TiO2 multiphase foam ceramic has good mechanical properties and high-temperature resistance.

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Development of an Aluminum-Based Hybrid Billet Material for the Process-Integrated Foaming of Hollow Co-Extrusions

Metals ◽

10.3390/met11091382 ◽

2021 ◽

Vol 11 (9) ◽

pp. 1382

Author(s):

Florian Patrick Schäfke ◽

Susanne Elisabeth Thürer ◽

Hans Jürgen Maier ◽

Christian Klose

Keyword(s):

Adhesive Bond ◽

Extrusion Process ◽

High Energy ◽

Scanning Calorimetry ◽

Foaming Agent ◽

Process Route ◽

Precursor Material ◽

Foaming Behavior ◽

Billet Material ◽

High Energy Absorption

Metal foams are attractive for lightweight construction in the automotive sector since they provide high-energy absorption and good damping properties, which is crucial, e.g., for crash structures. Currently, however, foams are produced separately and then pasted into the components. Consequently, the overall mechanical properties depend significantly on the quality of the adhesive bond between the foam and the structural component. A new process route for the manufacture of hybrid foamed hollow aluminum profiles is proposed. In this approach, a foamable precursor material is directly integrated into the extrusion process of the hollow structural profile. To this end, special low-melting alloys were developed in this study to enable foaming inside the aluminum profile. The melting intervals of these alloys were examined using differential scanning calorimetry. One of the promising AlZnSi alloys was atomized, mixed with a foaming agent and then compacted into semi-finished products for subsequent co-extrusion. The foaming behavior, which was investigated by means of X-ray microscopy, is shown to depend primarily on the mass fraction of the foaming agent as well as the heat treatment parameters. The results demonstrate that both the melting interval and the foaming behavior of AlZn22Si6 make this particular alloy a suitable candidate for the desired process chain.

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Production of Ceramics Reinforced Al Foams by Powder Metallurgy Techniques

Materials Science Forum ◽

10.4028/www.scientific.net/msf.672.39 ◽

2011 ◽

Vol 672 ◽

pp. 39-46

Author(s):

Mehmet Turker

Keyword(s):

Pore Structure ◽

Volume Fraction ◽

Linear Expansion ◽

Experimental Studies ◽

Three Dimensional ◽

Al Alloy ◽

Compaction Process ◽

Foaming Agent ◽

Foaming Behavior ◽

Al Foam

Powders metallurgy route was used to produce foams from pure Al powders and pre-alloyed Al alloy powders (Alumix 231) with or without reinforcing elements addition. Both classical Al foam and spherical Al foam were produced with various production parameters and the results obtained have been discussed. SiC particles were used as reinforcing elements and TiH2 powders were used as foaming agent. Prior to compaction process, Al powders, reinforcing element and foaming agent were mixed in a three dimensional turbula for 30 min. Mixed powders were compacted, sintered and deformed and then foamed at 690 oC for spherical foam and 710 oC for classical foam. Effect of volume fraction of reinforcing elements, foaming temperatures and foaming agent amounts on the foaming behavior, pore structure, pore distribution, linear expansion rate, density and wall thickness of the cell were investigated. Experimental studies have shown that 1% foaming agent and 4 % SiC addition was found to be the most suitable for foaming. In general foam produced from Alumix 231 powders exhibited more homogenous pore structure compared to the ones produced from pure Al powders.

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Foaming behavior of poly(lactic acid) with different D-isomer content based on supercritical CO2-induced crystallization

Journal of Cellular Plastics ◽

10.1177/0021955x20950242 ◽

2020 ◽

pp. 0021955X2095024

Author(s):

Jinwei Chen ◽

Ling Yang ◽

Qunshan Mai ◽

Mei Li ◽

Lixuan Wu ◽

...

Keyword(s):

Cellular Structure ◽

Poly Lactic Acid ◽

Foaming Agent ◽

Isomer Content ◽

Foaming Behavior ◽

Banded Spherulites ◽

Foaming Temperature ◽

Crystalline Domains ◽

Spherulite Morphology ◽

Induced Crystallization

Using supercritical carbon dioxide (sc-CO2) as a physical foaming agent, the effect of sc-CO2 on the formation of crystalline domains and subsequently on the foaming behaviors of the two grades of PLA with different D-isomer content were investigated in a wide foaming temperature range. The PLA’s final crystallinity is significantly increased with decreasing annealing temperature and by reducing the D-isomer content. Cellular structure results show that not only the crystallinity but also the crystalline morphology play an important role in cellular structure. A novel spherulite morphology including ringless and ring-banded morphology in the same spherulite was formed at lower foaming temperature, as a result, some entities were nonuniformly distributed in the PLA foams. Uniform and closed cellular structure were obtained when only the ring-banded spherulites were formed. An opened and interconnected cellular structure is tended to be formed because of the synergistic effect of high temperature and plasticization of CO2. Based on the crystallinity and morphology, a suitable foaming window as a function of temperature is proposed. It is found that PLA with 4.1% D-isomer content had much broader suitable foaming window range to produce homogeneous cellular structure.

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Influence of Material and Arrangement Mold on the Foaming Behavior of Extruded Precursor

Materials Science Forum ◽

10.4028/www.scientific.net/msf.933.92 ◽

2018 ◽

Vol 933 ◽

pp. 92-96

Author(s):

Fang Wang ◽

Lu Cai Wang

Keyword(s):

Pore Structure ◽

Powder Compact ◽

Orthogonal Test ◽

Furnace Temperature ◽

Foam Expansion ◽

Foaming Agent ◽

Foaming Behavior ◽

Hollow Part ◽

Foaming Time

In this paper, the extruded precursors were prepared by Powder compact method (PCM),with two different powder AlSi10 or pure Al mixed foaming agent ZrH2 or TiH2, then they were foamed to fill the hollow part. L9 (33) orthogonal test was planned, including three factors, furnace temperature; foaming time; and arrangement mode. The results indicated that the pore structure were effectively improved through adjusting the arrangement mode of precursors. The specimens have been obtained the homogeneous foam expansion when the AlSi10-TiH2 agent were arranged on the top while AlSi10-ZrH2 agent precursors at the bottom in the hollow, and foamed 14 min~16 min at 800 °C

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Effects of Nanoclay and CO2 Content on Foaming Behaviors of PP/PS Alloys

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.898.107 ◽

2014 ◽

Vol 898 ◽

pp. 107-110

Author(s):

Ming Yi Wang ◽

Ru Min Zhu ◽

Nan Qiao Zhou ◽

Chul B. Park

Keyword(s):

Population Density ◽

Cell Size ◽

Cell Population ◽

Foaming Agent ◽

Foaming Process ◽

Microcellular Foaming ◽

Foaming Behavior ◽

Extrusion Foaming

Microcellular foaming behavior of polypropylene/polystyrene (PP/PS) composites with or without the addition of nanoclay was compared in an extrusion foaming process by using supercritical CO2 as the foaming agent. The influence of CO2 content on foaming of the composites was investigated in the study. Our experiment results demonstrated that the introduction of nanoclay dramatically improved the foaming of the PP/PS blends with increased cell-population density and decreased cell size. With the increase of CO2 injected in the foaming process, cell-population density of the foam samples further increased.

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