Honeycomb Structures of Bulk Metallic Glasses

A combination of lithography and thermoplastic forming allows us to fabricate honeycombs from bulk metallic glass (BMG) precisely and to manipulate its structure selectively. Characteristics of the honeycomb such as the ligament length, thickness, and radius of curvature at the joints of the cells are varied to determine how changes in these characteristics affect properties under uniaxial in‐plane compression testing. It is found that the deformation behavior of BMG honeycombs can be controlled through microstructural design, from brittle to ductile, by changing the length to thickness ratio of the ligaments. The ability to absorb energy of BMG honeycombs exceeds honeycombs of most other materials due to the utilization of a size effect, which result in plasticity. Besides the usage for BMG honeycombs, the technique provides a general method to effectively characterize complex microstructural architectures and tailoring these architectures to the specifications of the material used.     

Preparation Method for Ruthenium Catalysts Supported by Carbon‐Coated Aluminum Foams

A preparation method is proposed for coating aluminum and aluminum alloy foams with a porous carbon layer for application as a catalyst support. The polymerization of furfuryl alcohol with diluted oxalic acid was used as precursor for the carbon layer. The polymer layer was distributed by applying centrifugal forces via spinning foam substrates during the polymerization process to prevent clogging and for homogeneous growth of the polymer layer. A homogeneous deposition precipitation method was applied for incorporation of ruthenium on carbon‐coated foam substrates. The carbon coating was characterized by X‐ray tomography to measure the thickness distribution. The specific surface and pore volume distribution were determined by gas adsorption (BET) and mercury porosimetry. The prepared Ru/C foam catalysts were adopted as a stirrer in a rotating foam reactor for hydrogenation of glucose, a simple biomass model substance.     

浅谈钳压式声测管施工技术

通过工程实例，介绍钳压式声测管的工艺原理和质量控制要点，以此说明采用钳压式声测管施工技术相比传统声测管施工的诸多优点。     

Preparation and characterisation of metal powder slurries for use as precursors for metal foams made by gel casting

Abstract

Metal powder slurries were prepared by adding 316L stainless steel powder to a methylcellulose solution. The highly viscous solution, in combination with high particle loadings, hindered powder sedimentation. The efficacy of a dispersant to produce low viscosity slurry was assessed by measuring the torque required to stir the suspension, compared to that needed to stir the base solution under the same conditions. These measurements were in reasonable agreement with data from viscometry, indicating a dispersant addition of 1·5 wt-% (based on the mass of the powder added) was sufficient to reduce the viscosity to that for the base cellulose solution. Slurries containing 45 vol.-% of 316L powder in a 2 wt-% methylcellulose solution, to which a minimum of 1·5 wt-% dispersant had been added, had a viscosity of roughly 0·5 Pa s and is deemed suitable for the production of metal foams via dipping or by mechanical whisking methods.     

Influences of liners and magnetic flux concentrator on induced Joule heat in hot extruded billet

In the production of pipes by hot extrusion method,billets should be heated to a certain temperature before hot extrusion by induction heating. The segmented liners in the induction furnace can possibly affect the circumferential Joule heat generation,thus leading to an uneven temperature field. The commonly used magnetic flux concentrators ( MFC) can increase the temperature on both ends of the billet. In this paper,the possible effect of liners and the factors affecting the utilization of the MFC,including the permeability,dimension and position,are all numerically studied and determined.     

Quality Evaluation of Chile-flavored, Jerky-type Extruded Products from Meat and Potato Flour

Extruded, jerky-type products prepared from potato flour combined with either partially defatted chopped beef (PDCB), mechanically separated chicken (MSC) or chicken thigh meat (C) and flavored with three levels of Chile powder were evaluated by instruments and sensory methods. Meaty aroma was more intense than potato or Chile aromas in all samples. MSC product tended to have the darkest color. Shear strength, tensile strength and sensory analyses indicated Chile powder may be a binding agent, resulting in harder texture, particularly in C products. Meaty and black pepper were dominant flavor characteristics detected by sensory panelists. Overall, PDCB product containing 0.5% Chile was rated most desirable.     

INSTRUMENTAL MEASURES OF BITE FORCES ASSOCIATED WITH CRISP PRODUCTS

The usefulness of a bite force apparatus for measuring bite forces generated while biting extruded crisp snacks was assessed. Snacks were produced using a twin‐screw extruder, and their textural properties were modified by equilibrating to water activities ranging from 0.11 to 0.44. Maximum force to bite, stress, duration and area under the bite force curve were analyzed and compared to perceived sensory crispness, hardness, brittleness and sound duration evaluated by eight individuals. Maximum bite force and stress were significantly related to hardness, brittleness and crispness showing for the first time, and the relationship between sensory crispness of extruded crisp products and hardness was measured intraorally.     

南瓜粉对挤压米膳食血糖指数及品质的影响

针对稻米中可溶性碳水化合物含量高,食用后极易引起血糖升高,不适于糖尿病患者食用等问题。作者以燕麦粉、马铃薯全粉等为主要原料,研制一款适合糖尿病人的食疗挤压米。结果表明：南瓜粉添加量为质量分数15%时,体外消化实验血糖指数最低,GI值为68.36;扫描电镜观测到其截面平整,结构紧密;蒸煮后测其加热吸水率、膨胀率分别高至191.35%、266.67%,米汤可溶性固形物质量分数仅为26.042 mg/g;质构特性良好,米粒饱满,感官评分最高。     

Lightweight and High Impact Polypropylene Foam Fabricated via Ultra-Low Gas Pressure Injection Molding

Foamed materials play an important role in a lightweight design. Foam injection molding (FIM) is an advanced and convenient way to fabricate lightweight structural materials. Recently, a new foam injection molding machine is developed, which only needs ultra-low gas pressure to fabricate microcellular foam. As a universal plastic, polypropylene (PP) is widely used due to its good mechanical properties. But after foaming, the toughness of the PP tends to decrease. Herein, a lightweight and high-impact polypropylene foam is fabricated via the new FIM technology with an ultra-low nitrogen pressure of 6.5 MPa. PP/polyolefin elastomer (POE) foam with a tiny cell size of 4.13 µm and high cell density of 2.7 × 10⁹  cm⁻³ is successfully obtained. Owing to the superior cellular structure, compared with the pure PP foam, after adding the POE component, the maximum impact performance is increased by 465%. In this work, an easy-to-industrialized method for preparing lightweight and high-impact injection-molded PP foams are presented.