外文翻譯---碳結(jié)構(gòu)和固體顆粒侵蝕的保護(hù)高度多孔炭碳復(fù)合保溫材料的使用

1、<p>　　Microstructure and solid particle erosion of carbon based materials used for the protection of highly porous carbon-carbon composite thermal </p><p>　　insulation</p><p>　　R. I. BAXT

2、ER, R. D. RAWLINGS </p><p>　　Department of Materials, Imperial College of Science, Technology and Medicine, </p><p>　　London SW7 2BP, UK</p><p>　　Multiparticle erosion tests were

3、 performed on candidate coating (colloidal graphite paints) and cladding (dense carbonc—arbon composites and graphite foil) materials employed to protect porous carbon—carbon composite thermal insulation in vacuum and in

4、ert-gas furnaces that utilize inert gas quenching. The dependence of the erosion rate on the angle of incidence of the erodent was examined and related to the microstructure and the mechanisms of material removal as obse

5、rved by SEM. In addition, th</p><p>　　mainly held together by mechanical locking, and a ploughing-like mechanism. The addition of a thin CVD carbon layer to colloidal graphite paint improved performance, whe

6、reas the erosion resistance of the graphite foil was slightly degraded as the CVD layer was too thin to prevent the ploughing-like mechanism.</p><p>　　1. Introduction </p><p>　　A class of high

7、ly porous carbon—carbon (C—C) composites, with low densities in the range 0.1—0.4 Mg m\3, are utilized as thermal insulation in vacuum and inert-gas furnaces at temperatures up to2800 °C. A consequence of th

8、e vacuum-moulding process used in the production of the composite is that the discontinuous fibres are orientated into layers to form a two-dimensional planar random structure. The vast majority of the volume of

9、the composite consists of interconnected pores</p><p>　　2. Experimental procedure </p><p>　　2.1. Materials </p><p>　　The CBCF used as the substrate was a standard commercial m

10、aterial (density 0.18 Mg m\3) manufactured by Calcarb Ltd. The coating and cladding materials </p><p>　　were applied to the xy plane of the CBCF substrate (see the schematic diagram o

11、f CBCF structure in Fig. 1); the xy plane is perpendicular to the direction of minimum thermal conductivity and hence is most likely to be the exposed surface of the insulation in a furnace.

12、The coating and cladding materials exam- ined in this paper were all carbon based and they are listed in Table I. The coating materials are defined as those that bond independentl</p><p>　　graphite pain

13、t coatings that were applied to the CBCF substrate by brushing. The material was subsequently heat treated at 900 °C in nitrogen to carbonize the resin </p><p>　　constituent of the colloid. Highe

14、r density carbon— carbon composites ('1.3 Mg m\3) used as cladding pressure of 5 kPa. (Note that the CVD of carbon in the interior of a porous medium is sometimes termed chemical vapour infiltr

15、ation, CVI.) Another cladding material was graphite foil which was produced by Toyo Tanso by compressing exfoliated graphite ?akes in a rolling operation [23]. The foil is ?exible in nature and is predominant

16、ly held together by </p><p>　　2.2. Erosion testing </p><p>　　Multiparticle erosion tests were performed on a gas- blast type rig, as described by Carter et al. [24]. In this apparatu

17、s the erodent particles enter the rig via an aperture in the base of an open hopper. A venturi fitted in the system allows the particles to be entrained in the compressed air ?ow. After passi

18、ng through a nozzle with an 8 mm internal diameter, the particles strike the target at a stand-of distance of 40 mm. The target specimens had nomin</p><p>　　The erodent used was angular equiaxed silica

19、sand obtained from Hepworth Minerals and Chemicals Ltd, Redhill, UK. The erodent was sieved to particle sizes between 150 and 300 lm, the mean size (by weight) was 230 lm which was found

20、 by a laser difrac- tion method (Mastersizer 1005, Malvern Instruments Ltd, Malvern, UK). The velocity of the particles was 6 m s\1, found by the streaking camera technique at the position of the targe

21、t. This method </p><p>　　film. Erosion tests were carried out at angles of 30°, 45°, 60°, 75° and 90°. </p><p>　　Generally, the samples were impacted b

22、y a fixed mass of erodent, then cleaned and reweighed. This process was repeated and the accumulated mass loss plotted against the accumulated mass of erodent. The </p><p>　　erosion rate, exp

23、ressed in terms of mass removed perunit mass of erodent, was calculated from the gradient of these plots. However, in the case of the low-density CBCF substrate material, which was investigated for comparison

24、 purposes, a significant mass of erodent penetrated and was retained within the porous structure of the composite. When calculating the erosion rate, the mass of this penetrated erodent must be taken into acc

25、ount and therefore the erosion rate was fou</p><p>　　material was graphite foil which was produced by Toyo Tanso by compressing exfoliated graphite ?akes in a rolling operation [23]. The foil is ?exib

26、le in nature and is predominantly held together by mechanical locking, as no binder is used. Further samples were produced by subjecting the Calcoat coating and the graphite foil to a CVD t

27、reatment (samples designated#CVD in Table I) for a period of 75 h under the conditions described above. A more extensive d</p><p>　　2.3. Micro structural and surface observations </p><p>　　

28、Samples for optical microscopy were vacuum impregnated with resin and subsequently polished to a 1 lmfinish. Samples for SEM were mounted on to aluminium tabs and examined at an accelerating voltage of 20 kV. In

29、 the majority of cases, coating was not required due to the sufcient electrical conductivity of the carbon samples; however, where charging of retained silica erodent was evident in the erode

30、d samples, they were splutter coated with gold.</p><p>　　3. Results and discussion </p><p>　　3.1. Microstructure </p><p>　　The structure of CBCF insulation material is show

31、n in Fig. 1; the porosity content of this fibre network is exceptionally high with 87% of the volume of the composite consisting of open and interconnected pores. The orientation of the fi

32、bres is evident in the micrograph in which the fibres lie preferentially in xy planes (i.e. perpendicular to the z direction) but are random in direction within these planes. The thickness of the

33、 Calcoat </p><p>　　(Fig. 2a). However, as a result of the high porosity content and the interconnected nature of the porosity in the CBCF substrate, some of the paint penetrates up to a

34、 depth of 600 lm (Fig. 2b). Calcoat M consists of Calcoat colloidal graphite paint, which contains sub-micrometre carbon particles, with the addition of coarser carbon particles and short fibr

35、es ((50 lm). The coarser carbon particles increase the viscosity of the paint whic</p><p>　　The Calcoat#CVD is produced by depositing carbon from the gaseous phase on to the Calcoat coating in t

36、he CVD furnace. This process produces a layer of dense pyrolytic carbon about 5 lm thick on the surface of the paint coating with little penetration (Fig. 2d). </p><p>　　The FMI C

37、3 C—C composite is produced from polyacrylonitrile (PAN) precursor carbon fibre cloth, which is about 1.2 mm thick [21]. The cloth is impregnated with phenolic resin but it is evident that the resi

38、n does not adequately penetrate the fibre bundles (Fig. 3a). Large platelets of resin-based carbon (500 lm; 500 lm;40 lm) are found between the layers of woven cloth, as can be seen in the plan section m

39、icro- graph in Fig. 3b. This may result </p><p><b>　　外文資料譯文</b></p><p>　　碳結(jié)構(gòu)和固體顆粒侵蝕的保護(hù)高度多孔炭碳</p><p><b>　　復(fù)合保溫材料的使用</b></p><p>　　材料系，英國(guó)皇家理

40、工學(xué)院，技術(shù)和醫(yī)學(xué)，倫敦SW7 2BP,英國(guó)</p><p>　　多粒子侵蝕進(jìn)行了測(cè)試備用涂料,( 膠狀石墨油漆)和電鍍（密集的碳—亞邦復(fù)合材料和石墨信息）用來保護(hù)多孔碳材料—碳復(fù)合保溫在真空和惰性氣體熔爐,利用惰性氣體淬火。依賴性侵蝕率的發(fā)生率的角度考察了從微觀結(jié)構(gòu)與機(jī)制的材料切除率作為SEM觀察的結(jié)果。此外,效果很薄的化學(xué)氣象沉積(CVD)碳層上的油漆涂料和膠體石墨石墨鋁箔復(fù)合進(jìn)行了檢驗(yàn)。涂層和熔覆材料顯示一

41、個(gè)更大的抗侵蝕對(duì)所有角度的發(fā)病率比多孔碳復(fù)合材料。一般來說,最大的侵蝕速率是發(fā)現(xiàn)一個(gè)90度的入射角°，從流的垂直于表面的侵蝕和脆性斷裂是優(yōu)勢(shì)機(jī)制的材料切除。唯一的例外是石墨箔材料顯示角度為最大侵蝕角度為60°的發(fā)生率。對(duì)于這種材料,兩種機(jī)制是有效的:破壞石墨薄片，這主要是由機(jī)械性的鎖在一起，和像耕田一樣的機(jī)制。除了薄層膠體CVD碳石墨涂料性能的改善，而腐蝕能力的石墨鋁箔略退化為CVD層太瘦了防止像耕田一樣的機(jī)制。&l

42、t;/p><p><b>　　1 介紹</b></p><p>　　一個(gè)類的多孔碳(C-C)復(fù)合材料與低密度范圍0.1—0.4 mg/m3，運(yùn)用在真空和惰性保溫爐在高溫下到2800°C。結(jié)果真空成型工藝生產(chǎn)中所使用的復(fù)合材料纖維的成層不連續(xù)導(dǎo)向,形成一個(gè)二維平面隨機(jī)結(jié)構(gòu)。絕大多數(shù)的成交量復(fù)合由互聯(lián)網(wǎng)和光纖網(wǎng)絡(luò)是保稅交叉運(yùn)用離散區(qū)域的纖維碳矩陣而不是一個(gè)連續(xù)的矩陣

43、。由于這個(gè)原因,這些復(fù)合材料也被稱為碳保稅碳纖維(CBCF)。由于高孔隙度和纖維取向、導(dǎo)熱系數(shù)垂直于纖維層比較低,一個(gè)典型的有用的材料有表面密度0.20mg/m3是0.24 wm/1k/1℃的真空中2000℃。調(diào)查顯微組織、力學(xué)性能和熱性能，這些材料被運(yùn)用。(1997年查普曼大廳CBCF用于爐采用高技術(shù)應(yīng)用,如單晶增長(zhǎng)(例如,硅或砷化鎵) 或金屬熱處理。這個(gè)金屬的熱處理，如工具鋼,越來越開展的熔爐,利用氣體淬火(通常是氮是使用) 氣體淬

44、火可以降低周轉(zhuǎn)期的間歇過程或作為一個(gè)整體的一部分,熱處理制度。</p><p>　　天然氣的優(yōu)勢(shì)淬火熱處理中，相對(duì)于一個(gè)油淬火,冷卻速度是可以控制的；因此，它有可能減少對(duì)變形和開裂的組件。在氣體淬火、可吸入顆粒物可能成為吸引氣體流,以及撞擊與絕緣可能導(dǎo)致材料被切除。在充滿挑戰(zhàn)的環(huán)境下的氣體淬火,有一個(gè)要求CBCF侵蝕的保護(hù)使用更高密度的碳基涂層和熔覆材料。通常,韌性和脆性材料具有不同的侵蝕特點(diǎn)。特別有趣的是他們之

45、間關(guān)系的侵蝕率和入射角。韌性材料往往表現(xiàn)出最大的侵蝕在瞬間角度的影響,大約30°的金屬。另一方面,脆性材料，最大侵蝕是很清楚的,從流垂直于表面的侵蝕,材料切除率通常結(jié)果是形成或橫向裂縫，盡管這是一個(gè)方便的方法來優(yōu)化的材料腐蝕以這樣的方式進(jìn)行腐蝕, 它是一種簡(jiǎn)化,因?yàn)榍治g是發(fā)現(xiàn)依賴于其他因素,包括侵蝕條件，如從指向形狀和大小,以及微觀結(jié)構(gòu)的細(xì)節(jié)目標(biāo)材料。本文關(guān)注的是測(cè)定的顯微組織及有效改善耐蝕性的幾個(gè)備用涂料和推。給出的結(jié)果包括

46、穩(wěn)態(tài)侵蝕率作為函數(shù)的角度定義的條件下的沖擊。</p><p>　　整體目標(biāo)的進(jìn)程都是與顯微組織侵蝕現(xiàn)象的數(shù)據(jù)相關(guān)的，通過一個(gè)機(jī)械的方法材料包括纖維材料有限公司。這是樹脂浸漬和隨后的吸化學(xué)氣相沉積(CVD)。 此外,一個(gè)高密度碳復(fù)合材料由使用CVD在一段800 h滲透到5毫米厚的部分CBCF襯底一個(gè)密度的3 m/mg。心血管疾病過程使用天然氣,作為碳和氮的前身為載體氣體。致密化將在大約1100°C在縮水。

47、</p><p><b>　　2 實(shí)驗(yàn)過程</b></p><p>　　這個(gè)CBCF用作基體上標(biāo)準(zhǔn)的商業(yè)材料(密度0.18mg/m3),公司生產(chǎn)的涂層和熔覆材料,應(yīng)用在x y平面上的CBCF基質(zhì);x y平面方向垂直,最小導(dǎo)熱系數(shù),因此是最有可能被暴露在表面的絕緣的熔爐中。涂層和熔覆材料測(cè)定——在本文中都是碳基及它們?cè)诒砻嫱繉硬牧?，是指那些性能自行以CBCF襯底,就像

48、推保稅通過一輛車——波蘭特水泥。石墨油漆涂料,也應(yīng)用于以CBCF襯底的。隨后的材料熱處理900°C碳氮樹脂。</p><p>　　組成的膠，密度高碳-碳復(fù)合材料作熔覆壓力5 kPa(注意,多粒子中碳的多孔介質(zhì)內(nèi)部的是有時(shí)被稱為化學(xué)蒸氣滲透)。另一個(gè)熔覆材料是石墨箔制作是通過壓縮剝落石墨薄片在滾動(dòng)來操作的。石墨具有靈活的性質(zhì)的,主要是由機(jī)械鎖在一起,因?yàn)闆]有使用額度的話。進(jìn)一步的樣本產(chǎn)生不利涂料和石墨襯多

49、粒子(樣本指定CVD的試樣)，在一段75 h上面描述的條件下。</p><p><b>　　2.1侵蝕測(cè)試</b></p><p>　　多粒子侵蝕測(cè)試進(jìn)行氣體——爆炸類型測(cè)定,被描述為卡特。在這個(gè)裝置從粒子進(jìn)入通過孔徑鉆機(jī)在基地的一個(gè)開放的環(huán)境。文丘里安裝在系統(tǒng)允許粒子傳遞壓縮空氣中流動(dòng)。在通過一個(gè)噴嘴內(nèi)部直徑著一個(gè)8毫米,粒子襲擊的目標(biāo)的一個(gè)站點(diǎn)的40mm的距離。目

50、標(biāo)標(biāo)本表面尺度25mm、12.5mm、5mm。</p><p>　　從使用的角度晶粒得到硅砂礦物質(zhì)，運(yùn)用于化工廠。從篩的是粒子大小在150nm到300nm之間、平均大小(重量)是230mg/m。發(fā)現(xiàn)由激光的方法。粒子的速度是按年代算的,發(fā)現(xiàn)的表面攝像技術(shù)在這個(gè)方位。這個(gè)方法涉及各行各業(yè)，即為已知的時(shí)間長(zhǎng)度測(cè)量線的長(zhǎng)度,粒子的產(chǎn)生光影。侵蝕試驗(yàn)角度在30°、45°、60°角,長(zhǎng)度在75

51、nm和90nm。</p><p>　　通常,這些樣品是一個(gè)固定的角度控制質(zhì)量的,然后再清洗和再稱重。這個(gè)過程被重復(fù)和累積的質(zhì)量損失從多次的循環(huán)中記錄。根據(jù)這些實(shí)驗(yàn)的梯度，這個(gè)侵蝕率,在數(shù)量上表現(xiàn)為大規(guī)模被切除。然而, 為了進(jìn)行比較研究，在低密度的情況下CBCF基體材料,,從一個(gè)重要的角度滲透,是保留在多孔結(jié)構(gòu)的復(fù)合材料。當(dāng)計(jì)算其腐蝕率、大規(guī)模的從滲透時(shí)，必須被考慮的。因此侵蝕率以下列方式被發(fā)現(xiàn)，每個(gè)示例只獲得了從

52、單劑量，總質(zhì)量變化的每一份樣本。另一個(gè)包覆材料石墨箔控制是通過壓縮剝落石墨薄片在滾動(dòng)操作。</p><p>　　2.2 微觀結(jié)構(gòu)和表面的觀察</p><p>　　樣本用于光學(xué)顯微鏡真空浸漬樹脂和隨后拋光。掃描電鏡樣品,安裝在選項(xiàng)卡并檢查了鋁在加速電壓20千伏。在大多數(shù)情況下,不需要涂料由于碳樣品的電導(dǎo)率;但是,充電的狀態(tài)從硅膠中顯侵蝕樣本。</p><p><

53、;b>　　3 結(jié)果和討論</b></p><p>　　CBCF絕緣材料的結(jié)構(gòu),孔隙度的內(nèi)容的網(wǎng)絡(luò)是異常高的，達(dá)87%的復(fù)合構(gòu)成的開放和互聯(lián)的基礎(chǔ)。纖維的方向是顯而易見的顯微纖維，優(yōu)先在x y平面(即垂直于z方向)但方向隨意在這些空間運(yùn)用。厚度的膠狀石墨油漆涂料是可變的,由于篩選方法的應(yīng)用,但通常介于40lm。然而,由于高孔隙率的原因和相互聯(lián)系的本質(zhì)在CBCF基質(zhì)孔隙度,一些油漆滲透到深度600

54、lm。膠狀石墨油漆,其中包含微碳粒子,加上較粗的碳顆粒和短纖維((50lm)。碳顆粒較粗的增加的粘度涂料,結(jié)果在一個(gè)較厚的表面涂層(80-200 lm)，通過最小化的程度滲透多孔基體的內(nèi)部。</p><p>　　這個(gè)多粒子是由把碳從氣態(tài)階段到涂層在CVD爐。這個(gè)過程可以產(chǎn)生一層致密熱解碳約5lm厚表面的油漆涂料,具有小的部分C3 C-C FMI的復(fù)合是由聚丙烯腈(PAN)前體碳纖維布,它是大約1.2毫米厚。布是用