北单比分中奖计算:Naure報道超級木材制造方法媲美鈦合金

北单比分奖金计算器 www.324103.live 每逢讀到醬紫的材料研究都很興奮,原理看似簡約,但一般人都想不到。特推薦給大家,最好讀一下參考文獻原文。

據外媒報道,鈦合金是我們打造過的最堅固的材料之一,但它們卻有一個致命缺點,那是又貴又重。現在,來自馬里蘭大學的科研人員已經為鈦合金找到了一個非常合適的替代品–“超級木”。通過一種全新的“致密化”技術,團隊成功制造出擁有跟鋼材一樣強度和韌度的“超級木”。

雖然木頭已經在多個領域找到用武之地,但馬里蘭大學的Liangbing Hu卻為它的這份清單中加入了更多的名字。Hu及其領導的團隊在過去幾年研發出了多種新型木材用途,如比玻璃還硬的透明木材、利用木材燃燒凈水、以木材和樹葉為基礎打造鈉離子電池。現在,他們又帶來了“超級木”。

首先,團隊需要在氫氧化鈉和亞硫酸鈉的混合水溶液下煮沸木材樣本,這一步驟主要為了去除木材中的木質素和半纖維素;然后通過熱壓將處理過的木材的細胞壁壓垮并形成規則排列的纖維素納米纖維。最終得到的則是完全致密的木材,這要比天然木材要堅固得多。

超級木材

Hu表示,通過這種方法處理過的木材的強度、韌性分別要比天然木材高出12倍、10倍?!罷夂苡鋅贍艸晌植納踔令押轄鸕撓辛赫?,它真的非常堅固耐用。同時它又可以跟碳纖維相媲美,但價格卻便宜得多?!?/p>

研究人員表示,這一技術可以應用到多種不同的木材,并且能一次性進行大量的處理。這將能為市場帶來能夠替代鋼材乃至鈦合金的更便宜、更輕的可再生材料。未來,它將能在汽車、飛機、建筑等任何使用到鋼材的領域找到用武之地。這項研究報告已發表在《自然》雜志上。

以上編譯內容轉自:CNBETA,僅供參考學習。

參考文獻:Processing bulk natural wood into a high-performance structural material,Nature volume 554, pages 224–228 (08 February 2018)
doi:10.1038/nature25476

Abstract

Synthetic structural materials with exceptional mechanical performance suffer from either large weight and adverse environmental impact (for example, steels and alloys) or complex manufacturing processes and thus high cost (for example, polymer-based and biomimetic composites)1,2,3,4,5,6,7,8. Natural wood is a low-cost and abundant material and has been used for millennia as a structural material for building and furniture construction9. However, the mechanical performance of natural wood (its strength and toughness) is unsatisfactory for many advanced engineering structures and applications. Pre-treatment with steam, heat, ammonia or cold rolling10,11,12,13,14,15,16,17,18,19,20,21?followed by densification has led to the enhanced mechanical performance of natural wood. However, the existing methods result in incomplete densification and lack dimensional stability, particularly in response to humid environments14, and wood treated in these ways can expand and weaken. Here we report a simple and effective strategy to transform bulk natural wood directly into a high-performance structural material with a more than tenfold increase in strength, toughness and ballistic resistance and with greater dimensional stability. Our two-step process involves the partial removal of lignin and hemicellulose from the natural wood via a boiling process in an aqueous mixture of NaOH and Na2SO3?followed by hot-pressing, leading to the total collapse of cell walls and the complete densification of the natural wood with highly aligned cellulose nanofibres. This strategy is shown to be universally effective for various species of wood. Our processed wood has a specific strength higher than that of most structural metals and alloys, making it a low-cost, high-performance, lightweight alternative.

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