版塊導航: 正在加載中...

登錄注冊

應《網(wǎng)絡安全法》要求，自2017年10月1日起，未進行實名認證將不得使用互聯(lián)網(wǎng)跟帖服務。為保障您的帳號能夠正常使用，請盡快對帳號進行手機號驗證，感謝您的理解與支持！

24小時熱門版塊排行榜

北京石油化工學院2026年研究生招生接收調(diào)劑公告

返回列表

本帖產(chǎn)生 1 個翻譯EPI ，點擊這里進行查看

wanghaiju

金蟲 (正式寫手)

應助: 2 (幼兒園)
金幣: 620.2
散金: 100
紅花: 1
帖子: 358
在線: 85.6小時
蟲號: 1047538
注冊: 2010-06-25
性別: MM
專業(yè): 應用有機化學

[求助] 高分子論文翻譯求助

General characteristics of SiC-based woven fabrics
The typical XRD patterns of the as-received and heat-treated SiC-based ceramic woven fabrics are shown in Fig. 2. The peaks show some broadening due to the small grain size of the fibers. The existence of three peaks in the 2θvalues of 35.9, 60.2, and 71.8°showed the presence of β-SiC, detected in both the as-received and heat-treated samples. However, after the heat treatment an additional phase, SiO2(α-cristobalite), was identified at around the 2θvalue of 22.0°, indicating oxidation of the sample. This passive oxidation leads to the formation of a protective silica film, protecting the fibers from further oxidation [22]. Under equilibrium conditions, quartz is the stable phase at room temperature; however, in this case cooling from 1573 K (heat-treatment temperature) was not slow enough for reconstructive phase transitions from cristobalite to quartz, which resulted in a displacive transition, causing the distortion of cristobalite and the existence of α-cristobalite at room temperature [23].
Figure 3a shows the SEM micrographs of the as-received PN-type fibers. A continuous oxide layer can be observed on the surface of the fibers on the SEM
micrograph of the heat-treated PN (PN-H) fabric (Fig. 3b). In some areas the continuity of the oxide layer was lost,most probably during handling of the bundles in the course of the observation of the fracture surface. At a higher magnification, the thickness of the oxide layer around the fiber was determined to be ~1 μm (Fig. 3c). The morphology and structure of the S8-type fibers showed similar characteristics to the PN-type in both as-received and heat-treated states.

Micrographs of the as-received and heat-treated ZE8(ZE8-H)-type fibers are shown in Fig. 4a and b, respectively. In the case of the ZE8-H, detailed observations revealed that there was no clear continuous oxide layer around the fibers, but rather only localized oxidation of the fiber, indicated by arrows in Fig. 4b. The ZE8 fabric is described as heat resistant by the manufacturer, a claim that is verified by the results of our experiments.

回復此樓

» 猜你喜歡

求化學調(diào)劑已經(jīng)有5人回復
085600，材料與化工321分求調(diào)劑已經(jīng)有10人回復
求調(diào)劑已經(jīng)有4人回復
0703 化學求調(diào)劑，一志愿山東大學 342 分已經(jīng)有5人回復
一志愿南開大學0710生物學359求調(diào)劑已經(jīng)有3人回復
085600，專業(yè)課化工原理，320分求調(diào)劑已經(jīng)有4人回復
材料與化工272求調(diào)劑已經(jīng)有16人回復
290求調(diào)劑已經(jīng)有3人回復
327求調(diào)劑已經(jīng)有3人回復
085600 286分材料求調(diào)劑已經(jīng)有11人回復

1樓 2014-06-11 10:33:25

已閱回復此樓關注TA 給TA發(fā)消息送TA紅花 TA的回帖

blacklight

木蟲 (著名寫手)

翻譯EPI: 2
應助: 45 (小學生)
金幣: 1811
散金: 5494
紅花: 15
帖子: 1328
在線: 559.1小時
蟲號: 848969
注冊: 2009-09-16
性別: GG
專業(yè): 污染控制化學

【答案】應助回帖

★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★
RXMCDM: 金幣+1 2014-06-12 20:47:34
wanghaiju: 金幣+35, 翻譯EPI+1, ★★★很有幫助 2014-06-12 22:12:07

基于SiC的編織纖維（這個詞我查的百度）的基本表征：
購買的和熱處理過的基于SiC的陶瓷編織纖維的XRD譜圖如圖2所示。由于纖維的晶粒尺寸比較小，所以譜圖中的峰寬比較寬。在購買的和熱處理過的樣品中，均出現(xiàn)了2θ=35.9, 60.2, 和 71.8°的衍射峰，說明這兩個樣品中都有β-SiC存在。在經(jīng)過熱處理后，因為有2θ=22.0°的衍射峰出現(xiàn)，所以可以確定樣品中存在SiO2(α-cristobalite)。這也說明了在熱處理過程中樣品被氧化了。這種氧化導致了一層保護性二氧化硅膜在樣品表面形成，從而避免了纖維的進一步氧化。在平衡態(tài)下，石英在室溫下是一種穩(wěn)定相。然而，從1573K冷卻的時候，由于冷卻速度沒有足夠慢，因此，晶相從方晶石相向石英相的轉(zhuǎn)化沒有徹底完成，從而導致了位移性轉(zhuǎn)化（這個詞不確定），引起方晶石相的扭曲，因而在室溫下也存在方晶石相。
圖3a為購買的PN-type纖維的掃描電鏡照片。從照片中，可以看到在熱處理的PN纖維表面上出現(xiàn)了一個連續(xù)的氧化層（圖3b）。在有些區(qū)域，這種連續(xù)的氧化層也會出現(xiàn)斷裂，這可能是因為在觀察斷裂表面的過程中對樣品處理時造成的。在更高的放大倍數(shù)下，氧化層的厚度被測定為1微米（圖3C）。S8纖維的形貌和結(jié)構(gòu)特征與購買的和經(jīng)過熱處理的PN纖維類似。
購買的和經(jīng)過熱處理的ZE8(ZE8-H)型纖維的形貌如圖4a和4b所示。對于ZE8-H來說，通過仔細觀察發(fā)現(xiàn)在它的表面沒有明顯的連續(xù)氧化層，然而這種纖維的局部出現(xiàn)了氧化現(xiàn)象，這些區(qū)域在圖4b中已經(jīng)被箭頭標注出來。生產(chǎn)商認為ZE8纖維是一種抗熱型材料，我們的實驗結(jié)果驗證了這一觀點。

樓主。別忘了懸賞的35個金幣啊！

贊一下(1人)

回復此樓

2樓2014-06-12 20:09:10