Fixation of Compressed Wood Using Melamine-Formaldehyde Resin

Methods to maximize wood hardness and dimensional stability include various combinations of compression, heating, and chemical treatment. In this study, wood was treated with increasing concentrations of a low molecular weight, water-soluble melamine-formaldehyde resin solution (mol wt 380) and compressed while heated. This method achieved a maximum bulking efficiency of 5% and an antishrink efficiency of 45%, showing that the chemical had not completely penetrated the cell wall. Once the wood was treated, its ability to retain the compressed state was tested by immersing wood specimens in water at different temperatures. Specimens treated with an 8% resin solution retained almost complete fixation when soaked in room-temperature water, while those treated with a 25% solution retained fixation in boiling water. Moreover, a 25% solution of resin and a compression of 54% increased hardness from 0.48 to 0.72 MPa

A REPORT ON THE PHYSICAL FITNESS AT NAGAOKA NATIONAL COLLEGE OF TECHNOLOGY IN 2006

本報告は、平成18年度に実施した長岡高専生のスポーツ・テストの調査結果をまとめたものである。18年度のスポーツテストの結果をみると、ほぼすべての学年で統計的に有意差が認められ、劣位な体力要素は、17年度と同様に、1)男子上体起こし、2)男子反復横とび、3)男女50m走、4)男子ハンドボール投げ、5)男子20mシャトルランの5項目と、6)男子長座体前屈が追加され、6項目であった。本校学生は、男女ともに全国平均値を上回る項目が少ない状況にあり、統計的にも明らかに劣っているといえる。また、すべての学年で有意差があった50m走の体力レベルをみると、男子は全国の13、14歳(中学2、3年生)、女子は9、10歳(小学4、5年生)レベルと同等の傾向を示す

Erosion Resistance Properties of Iron–Carbon Composite Plating to Molten Lead-Free Solder

The use of Sn-3mass%Ag-0.5mass%Cu lead-free solder (SAC305) has become common. Since SAC305 has a higher content of tin than conventional tin–lead eutectic solder, erosion of the Fe plating layer used in the solder iron tip and the point soldering machine nozzle frequently occurs. In this study, to prolong the life of the Fe plating layer, the applicability of composite plating in which a carbon-type filler is compounded with Fe was studied. Graphite and a multi-walled carbon nanotube (MWCNT) were used as filler materials in the composite plating layer. For both Fe-graphite and Fe-MWCNT composite plating layers, solderability testing and erosion-resistance testing were carried out. In the solderability test, although the spread rates of SAC305 to both Fe-graphite and Fe-MWCNT plating layers slightly decreased compared to the Fe plating layer, SAC305 solder was not repelled against both plating layers. In the erosion-resistance test, the Fe-MWCNT composite plating layer performed the best with the least erosion depth. The erosion depth of the Fe-graphite composite plating layer and the Fe plating layer were 10 and 100 times larger than that of the Fe-MWCNT composite plating layer, respectively. It was confirmed that the diffusion of Fe into molten SAC305 could be greatly reduced due to the composing carbon filler in Fe

Erosion Resistance of Iron-Boron Nitride Composite Plating to Molten Lead-Free Solder

In accordance with the EU RoHS Directive, the use of Sn3 mass%Ag0.5 mass%Cu lead-free solder (SAC305) has become the standard in the manufacturing of electronics. Since SAC305 contains more tin than the conventional tin-lead eutectic solder, erosion of the Fe plating frequently occurs on a hand soldering iron tip and a point soldering machine nozzle. In this study, to extend the life of the Fe plating layer, we investigated the applicability of a composite plating in which Fe is combined with the boron nitride (BN) compounds. We used BN particles as the bulk material, and boron nitride nanotubes (BNNT) as a nanomaterial, to fabricate the regarded composite materials. A solderability test and an erosion resistance test were conducted on the composite plating layer, made of both Fe-BN particles and Fe-BNNTs composites. In the solderability test, the spreading factor of SAC305 on the Fe-BN particle and on the Fe-BNNT composite platings were about the same as, or a little decreased compared to, that of the bare Fe plating. The SAC305 solder was not repelled by either composite plating. In the erosion resistance test, the Fe-BNNT composite plating performed the best, and had the lowest erosion depth. The erosion depths of the Fe-BN particle composite plating and the Fe plating ranged from about 6 to 24 times greater, respectively, than those of the Fe-BNNT composite plating layer, confirming that, in a nanomaterial BNNT-base, composite diffusion of Fe into SAC 305 can be suppressed

Infrared Spectroscopic and Computational Studies on Li4FeH6 with High Gravimetric Hydrogen Density

We report the vibrational properties of Li4FeH6 with the highest gravimetric hydrogen density in Fe-based complex hydrides. The Fouriertransform infrared (FTIR) spectrum shows a broad and weak peak at 600–1000 cm−1 and an intense one at 1400–1800 cm−1, which are assignedwith the aid of 1first-principles calculations to be the H–Fe–H bending modes, and the antisymmetric Fe–H stretching modes, respectively. Fromthe obtained peak frequency of asymmetric stretching modes of Li4FeH6, the Fe–H bond length is estimated to be 1.6 A, which is in good agreementwith the one predicted by fi1rst-principles calculations.