Al composite coatings with low infrared emissivity for high

The epoxy-siloxane/Al composite coatings with low infrared emissivity for high temperature applications

Chen Hu *,Guoyue Xu,Xingmei Shen,Chunming Shao,Xiaoxing Yan

College of Material Science &Engineering,Nanjing University of Aeronautics and Astronautics,Yu Dao Street 29,Nanjing 210016,China

1.Introduction

Low emissivity materials are widely used in civil and military applications such as heat loss control in industry or camou?aging military equipments [1,2].In recent years,low emissivity coating has received more considerable attention in many low emissivity materials.Extensive works on the low infrared emissivity coatings have been reported so far,such as nanosized silver colloids [3],dielectric/metal/dielectric multi-coatings [4,5],metallic thin ?lms [6,7],and inorganic/organic composite coatings [8–11].Especially,the inorganic/organic composite coatings composed of metallic pigments,like Cu and Al particles [12],and organic binder have the potential for applications in low infrared emissivity coatings.

However,the coatings applied in aircraft involve high friction heat from acute friction between aircraft surface and atmosphere,which causes high surface temperature during high speed ?ight [13].Unfortunately,most of the low emissivity inorganic/organic composite coatings present poor thermal resistance properties [3,9,14].Thus,the preparation of low emissivity coatings with good thermal resistance properties is of great importance for infrared stealth applications.Due to the high thermal stability in comparison to conventional organic polymers,silicones are frequently used in polymeric organic/inorganic composite coatings [15–17].The infrared emissivity of silicones is rather high [18,19],

and adding metallic pigment into silicones could contribute to the decrease of infrared emissivity.

In this paper,low emissivity composite coatings with good thermal resistance properties were prepared by direct incorpo-ration of preformed Al powder into epoxy-siloxane.The in?uence of chemical composition,surface texture,roughness and thickness on emissivity was studied.The above experimental results were combined with theoretical analysis to explain the emissivity properties of coatings.Furthermore,thermal ageing and thermal shock resistance of the composite coatings were also systemati-cally investigated.2.Experimental 2.1.Materials

Raw aluminum powder (particle size is $10m m),epoxy-siloxane (ES),dimethylbenzene and coupling agent g -amidopro-pyl-triethoxyl silicane (KH550).All the solvents were A.R.grade and used without further puri?cation.2.2.Pre-treated Al powder

0.1g KH550was dissolved in 10g ethanol to form KH550ethanol solution,and AL powder (3g)was added into above solution.Then,the system was ultrasonicated for 1h at room temperature.After ?ltration,the modi?ed Al powder was dried at 808C for 24h.Finally pre-treated Al powder was obtained.

Applied Surface Science 256(2010)3459–3463

A R T I C L E I N F O Article history:

Received 25September 2009

Received in revised form 15December 2009Accepted 15December 2009

Available online 23December 2009Keywords:

Infrared emissivity Thermal resistance Epoxy-siloxane Coating

A B S T R A C T

Low infrared emissivity coatings with good thermal resistance were prepared by using epoxy-siloxane and aluminum as adhesive and pigment,respectively.The in?uence of chemical composition,surface texture,roughness and thickness on the infrared emissivity was systematically investigated.The detailed results of experimental investigation indicate that the cured composite coatings could possess low emissivity value.Due to reducing infrared absorption and forming uniform and compact char construction,the infrared emissivity decreases obviously.Both the surface roughness and thickness have a critical value,respectively.Too large roughness or thickness would not contribute to the decrease of the emissivity.Moreover,the composite coatings were tested for thermal stability in air to explore the effect of high-temperature environment on the emissivity.The results indicate that the composite coatings,still possessing low emissivity after the test,exhibit favorable thermal ageing and thermal shock resistance.

?2009Elsevier B.V.All rights reserved.

*Corresponding author.Tel.:+862584892903;fax:+862584892951.E-mail address:huchen_zj@https://www.wendangku.net/doc/634590589.html, (C.Hu).Contents lists available at ScienceDirect

Applied Surface Science

j o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /a p s u s c

0169-4332/$–see front matter ?2009Elsevier B.V.All rights reserved.doi:10.1016/j.apsusc.2009.12.053

2.3.Pre-treated substrates

Tinplate substrates(12cm?5cm?0.3cm),properly cleaned at room temperature by10%dilute H2SO4and distilled water, respectively,were used as the coating substrate to measure the emissivity of different coatings.Tinplate is a non-homogeneous material with a strati?ed structure,basically consisting of a thin sheet of carbon steel coated with pure tin on both faces.According to the standard preparation method of coating(GB/T1727), tinplate was used as substrate for epoxy-siloxane/Al composite coating.

2.4.Preparation of composite coatings

Firstly,?xed amounts of epoxy-siloxane and dimethylbenzene were mixed5:1together to obtain the bond.Then,pre-treated Al powder were added into the bond under continuous ultrasonic wave for30min,and the weight concentration of Al power was ?xed at10%,20%,30%,40%and50%,respectively.

The mixture was painted onto the tin substrates by a spray

technique(98PSI,Japan)using an accurate speed motor(980r/ min)and appropriate pressure(7Mpa).The spray gun must be perpendicular to the substrates,and the distance between spray gun and substrate is about20cm.During spraying,the tempera-ture of substrate is20–258C,the carrier gas is air and the humidity of the air is40–50%.The spray rate(control air pressure(CAP))is 0.25m3/min and paint output is about95ml/min.

The coating thickness and surface roughness could be adjusted to different values,respectively.At last,there are two steps of curing procedure.The coatings were dried under vacuum at808C for5h?rstly,and then the obtained coatings were subjected to cured treatment completely for2h at3508C.

2.5.Characterization

Infrared emissivity value in8–14m m was measured using IR-2 Infrared Emissometer of Shanghai Institute of Technological Physics,China.The morphology and structures of samples were observed by scanning electron microscope(SEM)(FEI-Quanta200). Fourier-transform infrared spectroscopy(FTIR)was recorded on NEXUS-670Fourier transform infrared spectrophotometer using KBr pellets.The samples were prepared in0.2–0.25mm thickness KBr pellets(1mg in100mg of KBr).The surface roughness was observed by a Mahr perthometer S3P instrument(Germany).The thickness of coatings was measured by using a digital magnetism thickness instrument(China).

The thermal stability of ES/Al composite coatings was investigated through two tests.Firstly,the sample was heated externally in air to a designated temperature between4008C and 5508C and calcined for50h.This is called a thermal ageing test.In the second experiment,the sample was then heated to a designated temperature between4008C and5008C for10min followed by water quenching.The process was repeated for20 cycles.This is called a water-cooling thermal shock test.

3.Results and discussion

3.1.The effect of curing procedure on emissivity of ES/Al composite coatings

Fig.1shows FTIR spectra of the ES/40%Al composite coatings without and with curing procedures.The result of infrared spectra is not in?uenced by the substrate and surface roughness.As can be seen in Fig.1(a),the main absorption band,which is characteristic of siloxane,near1000–1130cmà1is related to the asymmetric Si–O–Si stretching.A peak appears near1605cmà1due to Si–C6H5vibrations.The peaks occurring at1510cmà1and1460cmà1are due to aromatic ring.The absorption peaks appearing at2960cmà1, 1260cmà1and840cmà1are attributed to Si–O–CH2CH3and Si–CH3,respectively[20].Fig.1(b)indicates that with curing procedure, the absorption bands are too weak to be observed except the band near1000–1130cmà1,and infrared absorption is greatly reduced. During the thermal degradation,the cleavage of Si–C bonds occurs, organo-groups release and side groups or chains are eliminated, which are accompanied by cross-linking reactions.Previous studies have revealed[21–24]that the primary degradation products are cyclic oligomeric siloxanes and higher oligomeric siloxane species. Such species cause cross-linking of degradation products.

The FTIR spectra of degradation products(Fig.1(b))indicate that the absorption bands are weaker and infrared absorption is greatly reduced.As we know by Kirchhoff’s law,at thermal equilibrium,the emissivity of a surface(or body)equals its absorbance,so the decrease of infrared absorption leads to lower emissivity[25].Therefore,the emissivity of the cured coatings is lower than that of the coating without cured.

The SEM image of the ES/40%Al composite coating after curing procedure is shown in Fig.2.From the?gure,it can be seen that Al particles are dispersed with signi?cant agglomeration,and clump together into clusters within the bonder.Both the FTIR and SEM results reveal that the surface of composite coating is char structure,which consists of Al particle and siloxane units after cured[26,27].This char structure indicates the formation of homogeneous cross-linking network of cured coating[28].

Table1shows the effect of curing procedure on the emissivity. From the table,it can be seen that the emissivity has drastic decrease after curing procedure.These results are consistent with above results of FTIR.According to Kirchhoff’s law and above discussion,the cured coatings have lower emissivity.All of following composite coatings are cured.

3.2.The effect of Al concentration on emissivity of ES/Al composite coatings

Fig.3shows the relationship between Al concentration and emissivity.From Fig.3and Section 3.1,it can be seen

the Fig.1.FTIR spectra of the ES/40%Al composite coatings,without cured(a),and with cured(b).

Table1

Effect of curing procedure on the emissivity.

Sample Emissivity

Without cured With cured 40%Al0.410.15

C.Hu et al./Applied Surface Science256(2010)3459–3463 3460

emissivity is greatly changed by the curing procedure and closely related to the Al concentration.The relationship between emissivity and Al concentration shows a ‘‘U’’shape.The emissivity of composite coatings (below 40wt%Al)decreases signi?cantly with increasing Al concentration,and approaches a lowest value 0.15when the Al concentration is about 40wt%.However,for the 50wt%Al composite coating,the emissivity of coating rises up to

0.18.The composite coatings with low Al concentration appear to have higher emissivity,whereas composite coatings show lower emissivity as we go for higher loading of Al powder.

The schematic diagram of the Al concentration with the emissivity and surface texture is shown in Fig.4.At low Al concentration,the Al particles are discretely dispersed,with relatively large inter-particle distances.Such a composite has high emissivity because most of coating surface is covered by bonder,as shown in Fig.5(a).With increasing Al concentration,the Al powder is incorporated and distributed throughout the coating.This phenomenon indicates that the char construction of coating surface has tendency to form uniform and compact surface,which leads to obvious decrease of emissivity.When the Al concentration rises up to 40%,all the Al particles coalesce into uniform and compact surface texture,as shown in Fig.5(b),which indicates that the change of coating emissivity is not obvious.

The increase of Al concentration would cause the closer packing of the Al particles in the composite coatings,resulting in the decrease of infrared emissivity.However,due to more amount of Al powder agglomeration resulting in non-uniform dispersion,which causes the increase of emissivity,the emissivity of 50wt%Al is higher than the emissivity of 40wt%Al.Therefore,it can be concluded that Al particles in the composite coating coalesce into uniform and compact surface texture at a saturation concentration.3.3.The effect of surface roughness on the emissivity of ES/Al composite coatings

The results of roughness and emissivity were listed in Table 2.Although all the samples are prepared by same Al concentration,the composite coatings with different processes have variable surface roughness values.From Table 2,it can be seen that the emissivity increases from 0.14to 0.20with increasing surface roughness from 0.92m m to 1.39m m.According to Section 3.2,the coating emissivity is mainly affected by the Al concentration.However,for the samples with same Al concentration,the different surface roughness causes different coating

emissivities.

Fig.2.SEM image of the ES/40%Al composite coating,without cured (a),and with cured

(b).

Fig. 3.The Al contentration dependence of infrared emissivity of composite

coatings.

Fig.4.Schematic diagram of the Al concentration with the emissivity and surface texture of composite coatings.

Table 2

Effect of surface roughness on emissivity of ES/40%Al composite coatings.Sample Roughness (m m)Emissivity 10.920.142 1.010.153 1.230.184

1.39

0.20

C.Hu et al./Applied Surface Science 256(2010)3459–34633461

As we knew,the lower surface roughness means smoother the coating surface.Bauer et al.[29]mentioned that polished and smooth surfaces have lower emissivity than those of rough surfaces.The relationship between emissivity and roughness is given by [30]:

e ?1àr g ?1àr r exp à

4pd

l

2

(1)

where r r and r g are the re?ectances for a rough surface and a polished surface,respectively,d is surface roughness and l is wavelength.When the coatings have similar surface texture,according to Eq.(1),high roughness leads to high emissivity.Therefore,the emissivity of composite coating with high rough-ness is higher than that with low roughness.

3.4.The effect of thickness on the emissivity of ES/40%Al composite coatings

Fig.6shows the thickness dependence of infrared emissivity of ES/40%Al coating.Since the samples were prepared by the same process,Al concentration and roughness,the emissivity was mainly effected by the coating thickness.In the past,the relationship between emissivity and coating thickness was explored in detail [31].Similar relationship was also found in this composite coating.From Fig.6,it can be seen that the emissivity decreases rapidly with increasing thickness,but approaches a

critical value when d >45m m.It can be explained easily from equation [32]:

e ?

e1àr e Te1àr b e à2Ad T

1àr e r b e à2Ad

(2)

where r e is the coating and air interface re?ectivity,r b is the substrate re?ectivity,d is the coating thickness,A is absorption coef?cient of unit volume.When the coating is not thick enough,the light can penetrate the thin coatings,thus the emissivity value is mostly in?uenced by the high emissivity substrate.When d !1,e à2Ad !0,then e =1àr e !constant.The emissivity keeps constant when thickness is as thick as possible.Although the unlimitedly thick coating could not be fabricated in practice,the light penetration depth is limited in general.Therefore,it is concluded that the composite coating,whose emissivity almost does not change,has a critical thickness about 45m m.3.5.The thermal property of ES/40%Al composite coating

The results of thermal stability test are listed in Table 3.From Table 3,it can be seen that the emissivity of composite coatings keeps constant when the calcination temperature is below 4508C.The coatings adhere to the substrate and the emissivity slightly increases from 0.16to 0.22after thermal ageing at 5008C.After thermal ageing test at 5508C,although small dark spots were found on the coating surface,the composite coatings did not spall,which indicates that it possesses a good thermal ageing resistance,as shown in Fig.7(a).However,the emissivity,which changed from 0.16to 0.66was greatly in?uenced by the small dark spots.After each thermal shock,the composite coatings were visually observed by SEM.The observation shows that it adhered well to the substrate up to 4508C.The composite coatings were

exfoliated

Fig.5.SEM images of ES/Al composite coatings:10%(a),and 40%

(b).

Table 3

Evaluation of thermal stability in air and emissivity values measured after thermal stability test.

Calcination temperature Thermal ageing test Calcination temperature 4008C 4508C 5008C 5508C 4008C 4508C 5008C *

**4**?Emissivity After test

0.16

0.16

0.22

0.66

0.16

0.16

0.87

*:good (coherence),?:exfoliated and 4:dark spots or crack were found on the surface.

C.Hu et al./Applied Surface Science 256(2010)3459–3463

3462

obviously at 5008C,as shown in Fig.7(b),resulting in a high emissivity up to 0.9.Since the composite coatings did not spall and emissivity did not change after the test,it is considered to be used for thermal shock of about 4508C.With increasing temperature,thermal degradation of organic adhesive is obvious and causes the coef?cients of thermal expansion (CTE)to change.The CTE of the substrate is 12–12.5?10à6/8C.When the calcination temperature is below 4508C,the CTE of composite coatings matched that of the substrate.But the CTE of composite coatings is different with that of the substrate when the temperature is above 5008C.The mismatch of CTE between the substrate and the coatings may lead to residual thermal stresses in the coatings,which cause composite coatings exfoliated in the test.According to the results of above test,it can be concluded that the ES/40%Al composite coatings with low emissivity generally exhibited favorable thermal ageing and excellent resistance to thermal shocking.

The superior thermal stability of the composite coatings is due to the formation of the cross-linking structured char,which consists of Al powder and siloxane units on the surface.To form a char structure on the surface of coating is an ef?cient way to enhance the thermal resistance property.Hshieh [33]suggested that the char structure could serve as a good insulating barrier,which reduces the incident heat ?ux by reradiating the external heat ?ux.Building upon work by previous researchers [34–37]demonstrated that the char structure could also act as a diffusion barrier,which suppresses the thermal degradation of the poly-mers,and restrains the diffusion of ?ammable degradation products into the combustion zone and the access of oxygen to the unburned degradation products.Consequently,low emissivity composite coatings exhibited good thermal stability properties.4.Conclusions

In summary,the epoxy-siloxane/Al composite coatings were prepared by a simple method.The lowest emissivity value of ES/40%Al composite coatings is 0.15in the range of 8–14m m.The emissivity of composite coatings was affected by chemical composition,surface texture,roughness and thickness.To reduce infrared absorption and form uniform and compact surface texture,the infrared emissivity decreases obviously.The high roughness causes high emissivity of the coating with the same Al concentration.The emissivity declines rapidly with increasing thickness and reaches to a critical value when d >45m m.In addition,the results of thermal property experiment show the emissivity almost maintained a low value below 5008C,and the composite coatings exhibited high thermal stability and good thermal shock resistance in air.The composite coatings as low

infrared emissivity material may have great potential applications in high temperature conditions.Acknowledgements

This work was ?nancially supported by the National Natural Science Foundation of China under Grant No.90505008and Weaponry Equipment Pre-research Foundation of China.References

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C.Hu et al./Applied Surface Science 256(2010)3459–34633463

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with复合结构专项练习（二） 一请选择最佳答案 1）With nothing_______to burn，the fire became weak and finally died out. A.leaving B.left C.leave D.to leave 2）The girl sat there quite silent and still with her eyes_______on the wall. A.fixing B.fixed C.to be fixing D.to be fixed 3）I live in the house with its door_________to the south.（这里with结构作定语） A.facing B.faces C.faced D.being faced 4）They pretended to be working hard all night with their lights____. A.burn B.burnt C.burning D.to burn 二：用with复合结构完成下列句子 1）_____________（有很多工作要做），I couldn't go to see the doctor. 2）She sat__________（低着头）。 3）The day was bright_____.（微风吹拂） 4）_________________________，（心存梦想）he went to Hollywood. 三把下列句子中的划线部分改写成with复合结构。 1）Because our lessons were over，we went to play football. _____________________________. 2）The children came running towards us and held some flowers in their hands. _____________________________. 3）My mother is ill，so I won't be able to go on holiday. _____________________________. 4）An exam will be held tomorrow，so I couldn't go to the cinema tonight. _____________________________.

精神分裂症的病因及发病机理

精神分裂症的病因及发病机理 精神分裂症病因：尚未明，近百年来的研究结果也仅发现一些可能的致病因素。（一）生物学因素1．遗传遗传因素是精神分裂症最可能的一种素质因素。国内家系调查资料表明：精神分裂症患者亲属中的患病率比一般居民高6.2倍，血缘关系愈近，患病率也愈高。双生子研究表明：遗传信息几乎相同的单卵双生子的同病率远较遗传信息不完全相同 的双卵双生子为高，综合近年来11项研究资料：单卵双生子同病率（56.7%），是双卵双生子同病率（12.7%）的4.5倍，是一般人口患难与共病率的35-60倍。说明遗传因素在本病发生中具有重要作用，寄养子研究也证明遗传因素是本症发病的主要因素，而环境因素的重要性较小。以往的研究证明疾病并不按类型进行遗传，目前认为多基因遗传方式的可能性最大，也有人认为是常染色体单基因遗传或多源性遗传。Shields发现病情愈轻，病因愈复杂，愈属多源性遗传。高发家系的前瞻性研究与分子遗传的研究相结合，可能阐明一些问题。国内有报道用人类原癌基因Ha-ras-1为探针，对精神病患者基因组进行限止性片段长度多态性的分析，结果提示11号染色体上可能存在着精神分裂症与双相情感性精神病有关的DNA序列。2．性格特征：约40%患者的病前性格具有孤僻、冷淡、敏感、多疑、富于幻想等特征，即内向

型性格。3．其它：精神分裂症发病与年龄有一定关系，多发生于青壮年，约1/2患者于20～30岁发病。发病年龄与临床类型有关，偏执型发病较晚，有资料提示偏执型平均发病年龄为35岁，其它型为23岁。80年代国内12地区调查资料：女性总患病率（7.07%。）与时点患病率（5.91%。）明显高于男性（4.33%。与3.68%。）。Kretschmer在描述性格与精神分裂症关系时指出：61%患者为瘦长型和运动家型，12.8%为肥胖型，11.3%发育不良型。在躯体疾病或分娩之后发生精神分裂症是很常见的现象，可能是心理性生理性应激的非特异性影响。部分患者在脑外伤后或感染性疾病后发病；有报告在精神分裂症患者的脑脊液中发现病毒性物质；月经期内病情加重等躯体因素都可能是诱发因素，但在精神分裂症发病机理中的价值有待进一步证实。（二）心理社会因素1．环境因素①家庭中父母的性格，言行、举止和教育方式（如放纵、溺爱、过严）等都会影响子女的心身健康或导致个性偏离常态。②家庭成员间的关系及其精神交流的紊乱。③生活不安定、居住拥挤、职业不固定、人际关系不良、噪音干扰、环境污染等均对发病有一定作用。农村精神分裂症发病率明显低于城市。2．心理因素一般认为生活事件可发诱发精神分裂症。诸如失学、失恋、学习紧张、家庭纠纷、夫妻不和、意处事故等均对发病有一定影响，但这些事件的性质均无特殊性。因此，心理因素也仅属诱发因

with的用法大全

with的用法大全----四级专项训练with结构是许多英语复合结构中最常用的一种。学好它对学好复合宾语结构、不定式复合结构、动名词复合结构和独立主格结构均能起很重要的作用。本文就此的构成、特点及用法等作一较全面阐述，以帮助同学们掌握这一重要的语法知识。 一、 with结构的构成 它是由介词with或without+复合结构构成，复合结构作介词with或without的复合宾语，复合宾语中第一部分宾语由名词或代词充当，第二部分补足语由形容词、副词、介词短语、动词不定式或分词充当，分词可以是现在分词，也可以是过去分词。With结构构成方式如下： 1. with或without-名词/代词+形容词; 2. with或without-名词/代词+副词; 3. with或without-名词/代词+介词短语; 4. with或without-名词/代词+动词不定式; 5. with或without-名词/代词+分词。 下面分别举例：

1、 She came into the room，with her nose red because of cold.(with+名词+形容词，作伴随状语) 2、 With the meal over ， we all went home.(with+名词+副词，作时间状语) 3、The master was walking up and down with the ruler under his arm。(with+名词+介词短语，作伴随状语。) The teacher entered the classroom with a book in his hand. 4、He lay in the dark empty house，with not a man ，woman or child to say he was kind to me.(with+名词+不定式，作伴随状语) He could not finish it without me to help him.(without+代词 +不定式，作条件状语) 5、She fell asleep with the light burning.(with+名词+现在分词，作伴随状语) 6、Without anything left in the cupboard， she went out to get something to eat.(without+代词+过去分词，作为原因状语) 二、with结构的用法 在句子中with结构多数充当状语，表示行为方式，伴随情况、时间、原因或条件(详见上述例句)。

with用法归纳

with用法归纳 （1）“用……”表示使用工具，手段等。例如： ①We can walk with our legs and feet. 我们用腿脚行走。 ②He writes with a pencil. 他用铅笔写。 （2）“和……在一起”，表示伴随。例如： ①Can you go to a movie with me? 你能和我一起去看电影'>电影吗？ ②He often goes to the library with Jenny. 他常和詹妮一起去图书馆。 （3）“与……”。例如： I’d like to have a talk with you. 我很想和你说句话。 （4）“关于，对于”，表示一种关系或适应范围。例如： What’s wrong with your watch? 你的手表怎么了？ （5）“带有，具有”。例如： ①He’s a tall kid with short hair. 他是个长着一头短发的高个子小孩。 ②They have no money with them. 他们没带钱。 （6）“在……方面”。例如： Kate helps me with my English. 凯特帮我学英语。 （7）“随着，与……同时”。例如： With these words, he left the room. 说完这些话，他离开了房间。 [解题过程] with结构也称为with复合结构。是由with+复合宾语组成。常在句中做状语，表示谓语动作发生的伴随情况、时间、原因、方式等。其构成有下列几种情形： 1.with+名词(或代词)+现在分词 此时，现在分词和前面的名词或代词是逻辑上的主谓关系。 例如:1)With prices going up so fast, we can't afford luxuries. 由于物价上涨很快，我们买不起高档商品。（原因状语） 2)With the crowds cheering, they drove to the palace. 在人群的欢呼声中，他们驱车来到皇宫。（伴随情况） 2.with+名词(或代词)+过去分词 此时，过去分词和前面的名词或代词是逻辑上的动宾关系。

独立主格with用法小全

独立主格篇 独立主格，首先它是一个“格”，而不是一个“句子”。在英语中任何一个句子都要有主谓结构，而在这个结构中，没有真正的主语和谓语动词，但又在逻辑上构成主谓或主表关系。独立主格结构主要用于描绘性文字中，其作用相当于一个状语从句，常用来表示时间、原因、条件、行为方式或伴随情况等。除名词/代词+名词、形容词、副词、非谓语动词及介词短语外，另有with或without短语可做独立主格，其中with可省略而without不可以。*注：独立主格结构一般放在句首，表示原因时还可放在句末；表伴随状况或补充说明时，相当于一个并列句，通常放于句末。 一、独立主格结构： 1. 名词/代词+形容词 He sat in the front row, his mouth half open. Close to the bank I saw deep pools, the water blue like the sky. 靠近岸时，我看见几汪深池塘，池水碧似蓝天。 2. 名词/代词+现在分词 Winter coming, it gets colder and colder. The rain having stopped, he went out for a walk.

The question having been settled, we wound up the meeting. 也可以The question settled, we wound up the meeting. 但含义稍有差异。前者强调了动作的先后。 We redoubled our efforts, each man working like two. 我们加倍努力，一个人干两个人的活。 3. 名词/代词+过去分词 The job finished, we went home. More time given, we should have done the job much better. *当表人体部位的词做逻辑主语时，不及物动词用现在分词，及物动词用过去分词。 He lay there, his teeth set, his hands clenched, his eyes looking straight up. 他躺在那儿，牙关紧闭，双拳紧握，两眼直视上方。 4. 名词/代词+不定式 We shall assemble at ten forty-five, the procession to start moving at precisely eleven. We divided the work, he to clean the windows and I to sweep the floor.

精神分裂症的发病原因是什么

精神分裂症的发病原因是什么 精神分裂症是一种精神病，对于我们的影响是很大的，如果不幸患上就要及时做好治疗，不然后果会很严重，无法进行正常的工作和生活，是一件很尴尬的事情。因此为了避免患上这样的疾病，我们就要做好预防，今天我们就请广州协佳的专家张可斌来介绍一下精神分裂症的发病原因。 精神分裂症是严重影响人们身体健康的一种疾病，这种疾病会让我们整体看起来不正常，会出现胡言乱语的情况，甚至还会出现幻想幻听，可见精神分裂症这种病的危害程度。 (1)精神刺激：人的心理与社会因素密切相关，个人与社会环境不相适应，就产生了精神刺激，精神刺激导致大脑功能紊乱，出现精神障碍。不管是令人愉快的良性刺激，还是使人痛苦的恶性刺激，超过一定的限度都会对人的心理造成影响。 (2)遗传因素：精神病中如精神分裂症、情感性精神障碍，家族中精神病的患病率明显高于一般普通人群，而且血缘关系愈近，发病机会愈高。此外，精神发育迟滞、癫痫性精神障碍的遗传性在发病因素中也占相当的比重。这也是精神病的病因之一。 (3)自身：在同样的环境中，承受同样的精神刺激，那些心理素质差、对精神刺激耐受力低的人易发病。通常情况下，性格内向、心胸狭窄、过分自尊的人，不与人交往、孤僻懒散的人受挫折后容易出现精神异常。 (4)躯体因素：感染、中毒、颅脑外伤、肿瘤、内分泌、代谢及营养障碍等均可导致精神障碍，。但应注意，精神障碍伴有的躯体因素，并不完全与精神症状直接相关，有些是由躯体因素直接引起的，有些则是以躯体因素只作为一种诱因而存在。 孕期感染。如果在怀孕期间，孕妇感染了某种病毒，病毒也传染给了胎儿的话，那么，胎儿出生长大后患上精神分裂症的可能性是极其的大。所以怀孕中的女性朋友要注意卫生，尽量不要接触病毒源。 上述就是关于精神分裂症的发病原因，想必大家都已经知道了吧。患上精神分裂症之后，大家也不必过于伤心，现在我国的医疗水平是足以让大家快速恢复过来的，所以说一定要保持良好的情绪。

with用法小结

with用法小结 一、with表拥有某物 Mary married a man with a lot of money . 马莉嫁给了一个有着很多钱的男人。 I often dream of a big house with a nice garden . 我经常梦想有一个带花园的大房子。 The old man lived with a little dog on the lonely island . 这个老人和一条小狗住在荒岛上。 二、with表用某种工具或手段 I cut the apple with a sharp knife . 我用一把锋利的刀削平果。 Tom drew the picture with a pencil . 汤母用铅笔画画。 三、with表人与人之间的协同关系 make friends with sb talk with sb quarrel with sb struggle with sb fight with sb play with sb work with sb cooperate with sb I have been friends with Tom for ten years since we worked with each other, and I have never quarreled with him . 自从我们一起工作以来，我和汤姆已经是十年的朋友了，我们从没有吵过架。 四、with 表原因或理由 John was in bed with high fever . 约翰因发烧卧床。 He jumped up with joy . 他因高兴跳起来。 Father is often excited with wine . 父亲常因白酒变的兴奋。 五、with 表“带来”，或“带有,具有”，在…身上，在…身边之意

with复合宾语的用法(20201118215048)

with+复合宾语的用法 一、with的复合结构的构成 二、所谓"with的复合结构”即是"with+复合宾语”也即"with +宾语+宾语补足语” 的结构。其中的宾语一般由名词充当（有时也可由代词充当）；而宾语补足语则是根据 具体的需要由形容词，副词、介词短语，分词短语（包括现在分词和过去分词）及不定式短语充当。下面结合例句就这一结构加以具体的说明。 三、1、with +宾语+形容词作宾补 四、①He slept well with all the windows open.（82 年高考题） 上面句子中形容词open作with的宾词all the windows的补足语， ②It' s impolite to talk with your mouth full of food. 形容词短语full of food 作宾补。Don't sleep with the window ope n in win ter 2、with+宾语+副词作宾补 with Joh n away, we have got more room. He was lying in bed with all his clothes on. ③Her baby is used to sleeping with the light on.句中的on 是副词，作宾语the light 的补足语。 ④The boy can t play with his father in.句中的副词in 作宾补。 3、with+宾语+介词短语。 we sat on the grass with our backs to the wall. his wife came dow n the stairs,with her baby in her arms. They stood with their arms round each other. With tears of joy in her eyes ,she saw her daughter married. ⑤She saw a brook with red flowers and green grass on both sides. 句中介词短语on both sides 作宾语red flowersandgreen grass 的宾补， ⑥There were rows of white houses with trees in front of them.，介词短语in front of them 作宾补。 4、with+宾词+分词（短语 这一结构中作宾补用的分词有两种，一是现在分词，二是过去分词，一般来说，当分词所表 示的动作跟其前面的宾语之间存在主动关系则用现在分词，若是被动关系，则用过去分词。 ⑦In parts of Asia you must not sit with your feet pointing at another person.（高一第十课），句中用现在分词pointing at…作宾语your feet的补足语，是因它们之间存在主动关系，或者说point 这一动作是your feet发出的。 All the after noon he worked with the door locked. She sat with her head bent. She did not an swer, with her eyes still fixed on the wall. The day was bright,with a fresh breeze（微风）blowing. I won't be able to go on holiday with my mother being ill. With win ter coming on ,it is time to buy warm clothes. He soon fell asleep with the light still bur ning. ⑧From space the earth looks like ahuge water covered globe,with a few patches of land stuk ing out above the water而在下面句子中因with的宾语跟其宾补之间存在被动关系，故用过去分词作宾补：

精神分裂症的病因是什么

精神分裂症的病因是什么 精神分裂症是一种精神方面的疾病，青壮年发生的概率高，一般 在16～40岁间，没有正常器官的疾病出现，为一种功能性精神病。 精神分裂症大部分的患者是由于在日常的生活和工作当中受到的压力 过大，而患者没有一个良好的疏导的方式所导致。患者在出现该情况 不仅影响本人的正常社会生活，且对家庭和社会也造成很严重的影响。 精神分裂症常见的致病因素： 1、环境因素：工作环境比如经济水平低低收入人群、无职业的人群中，精神分裂症的患病率明显高于经济水平高的职业人群的患病率。还有实际的生活环境生活中的不如意不开心也会诱发该病。 2、心理因素：生活工作中的不开心不满意，导致情绪上的失控，心里长期受到压抑没有办法和没有正确的途径去发泄，如恋爱失败， 婚姻破裂，学习、工作中不愉快都会成为本病的原因。 3、遗传因素：家族中长辈或者亲属中曾经有过这样的病人，后代会出现精神分裂症的机会比正常人要高。 4、精神影响：人的心里与社会要各个方面都有着不可缺少的联系，对社会环境不适应，自己无法融入到社会中去，自己与社会环境不相

适应，精神和心情就会受到一定的影响，大脑控制着人的精神世界， 有可能促发精神分裂症。 5、身体方面：细菌感染、出现中毒情况、大脑外伤、肿瘤、身体的代谢及营养不良等均可能导致使精神分裂症，身体受到外界环境的 影响受到一定程度的伤害，心里受到打击，无法承受伤害造成的痛苦，可能会出现精神的问题。 对于精神分裂症一定要配合治疗，接受全面正确的治疗，最好的 疗法就是中医疗法加心理疗法。早发现并及时治疗并且科学合理的治疗，不要相信迷信，要去正规的医院接受合理的治疗，接受正确的治 疗按照医生的要求对症下药，配合医生和家人，给病人创造一个良好 的治疗环境，对于该病的康复和痊愈会起到意想不到的效果。

(完整版)with的复合结构用法及练习

with复合结构 一. with复合结构的常见形式 1.“with+名词/代词+介词短语”。 The man was walking on the street, with a book under his arm. 那人在街上走着，腋下夹着一本书。 2. “with+名词/代词+形容词”。 With the weather so close and stuffy, ten to one it’ll rain presently. 天气这么闷热，十之八九要下雨。 3. “with+名词/代词+副词”。 The square looks more beautiful than even with all the light on. 所有的灯亮起来，广场看起来更美。 4. “with+名词/代词+名词”。 He left home, with his wife a hopeless soul. 他走了，妻子十分伤心。 5. “with+名词/代词+done”。此结构过去分词和宾语是被动关系，表示动作已经完成。 With this problem solved, neomycin 1 is now in regular production. 随着这个问题的解决，新霉素一号现在已经正式产生。 6. “with+名词/代词+-ing分词”。此结构强调名词是-ing分词的动作的发出者或某动作、状态正在进行。 He felt more uneasy with the whole class staring at him. 全班同学看着他，他感到更不自然了。 7. “with+宾语+to do”。此结构中，不定式和宾语是被动关系，表示尚未发生的动作。 So in the afternoon, with nothing to do, I went on a round of the bookshops. 由于下午无事可做，我就去书店转了转。 二. with复合结构的句法功能 1. with 复合结构，在句中表状态或说明背景情况，常做伴随、方式、原因、条件等状语。With machinery to do all the work, they will soon have got in the crops. 由于所有的工作都是由机器进行，他们将很快收完庄稼。（原因状语） The boy always sleeps with his head on the arm. 这个孩子总是头枕着胳膊睡觉。（伴随状语）The soldier had him stand with his back to his father. 士兵要他背对着他父亲站着。（方式状语）With spring coming on, trees turn green. 春天到了，树变绿了。（时间状语） 2. with 复合结构可以作定语 Anyone with its eyes in his head can see it’s exactly like a rope. 任何一个头上长着眼睛的人都能看出它完全像一条绳子。 【高考链接】 1. ___two exams to worry about, I have to work really hard this weekend.（04北京） A. With B. Besides C. As for D. Because of 【解析】A。“with+宾语+不定式”作状语，表示原因。 2. It was a pity that the great writer died, ______his works unfinished. (04福建) A. for B. with C. from D.of 【解析】B。“with+宾语+过去分词”在句中作状语，表示状态。 3._____production up by 60%, the company has had another excellent year. (NMET) A. As B.For C. With D.Through 【解析】C。“with+宾语+副词”在句中作状语，表示程度。

With复合结构的用法小结

With复合结构的用法小结 with结构是许多英语复合结构中最常用的一种。学好它对学好复合宾语结构、不定式复合结构、动名词复合结构和独立主格结构均能起很重要的作用。本文就此的构成、特点及用法等作一较全面阐述，以帮助同学们掌握这一重要的语法知识。 一、with结构的构成 它是由介词with或without+复合结构构成，复合结构作介词with或without的复合宾语，复合宾语中第一部分宾语由名词或代词充当，第二 部分补足语由形容词、副词、介词短语、动词不定式或分词充当，分词可以是现在分词，也可以是过去分词。With结构构成方式如下： 1. with或without-名词/代词+形容词； 2. with或without-名词/代词+副词； 3. with或without-名词/代词+介词短语； 4. with或without-名词/代词+动词不定式； 5. with或without-名词/代词+分词。 下面分别举例： 1、She came into the room，with her nose red because of cold.（with+名词+形容词，作伴随状语） 2、With the meal over ，we all went home.（with+名词+副词，作时间状语） 3、The master was walking up and down with the ruler under his arm。（with+名词+介词短语，作伴随状语。）The teacher entered the classroom with a book in his hand. 4、He lay in the dark empty house，with not a man ，woman or child to say he was kind to me.（with+名词+不定式，作伴随状语）He could not finish it without me to help him.（without+代词+不定式，作条件状语） 5、She fell asleep with the light burning.（with+名词+现在分词，作伴随状语）Without anything left in the cupboard，shewent out to get something to eat.（without+代词+过去分词，作为原因状语） 二、with结构的用法 在句子中with结构多数充当状语，表示行为方式，伴随情况、时间、原因或条件（详见上述例句）。 With结构在句中也可以作定语。例如： 1.I like eating the mooncakes with eggs. 2.From space the earth looks like a huge water-covered globe with a few patches of land sticking out above the water. 3.A little boy with two of his front teeth missing ran into the house. 三、with结构的特点 1. with结构由介词with或without+复合结构构成。复合结构中第一部分与第二部分语法上是宾语和宾语补足语关系，而在逻辑上，却具有主谓关系，也就是说，可以用第一部分作主语，第二部分作谓语，构成一个句子。例如：With him taken care of，we felt quite relieved.（欣慰）→（He was taken good care of.）She fell asleep with the light burning. →（The light was burning.）With her hair gone，there could be no use for them. →（Her hair was gone.） 2. 在with结构中，第一部分为人称代词时，则该用宾格代词。例如：He could not finish it without me to help him. 四、几点说明： 1. with结构在句子中的位置：with 结构在句中作状语，表示时间、条件、原因时一般放在

with的用法

with[wIT] prep.1.与…(在)一起，带着：Come with me. 跟我一起来吧。/ I went on holiday with my friend. 我跟我朋友一起去度假。/ Do you want to walk home with me? 你愿意和我一道走回家吗 2.(表带有或拥有)有…的，持有，随身带着：I have no money with me. 我没有带钱。/ He is a man with a hot temper. 他是一个脾气暴躁的人。/ We bought a house with a garden. 我们买了一座带花园的房子。/ China is a very large country with a long history. 中国是一个具有历史悠久的大国。3.(表方式、手段或工具)以，用：He caught the ball with his left hand. 他用左手接球。/ She wrote the letter with a pencil. 她用铅笔写那封信。4.(表材料或内容)以，用：Fill the glass with wine. 把杯子装满酒。/ The road is paved with stones. 这条路用石头铺砌。5.(表状态)在…的情况下，…地：He can read French with ease. 他能轻易地读法文。/ I finished my homework though with difficulty. 虽然有困难，我还是做完了功课。6.(表让步)尽管，虽然：With all his money, he is unhappy. 尽管他有钱，他并不快乐。/ With all his efforts, he lost the match. 虽然尽了全力，他还是输了那场比赛。7.(表条件)若是，如果：With your permission, I’ll go. 如蒙你同意我就去。8.(表原因或理由)因为，由于：He is tired with work. 他工作做累了。/ At the news we all jumped with joy. 听到这消息我们都高兴得跳了起来。9.(表时间)当…的时候，在…之后：With that remark, he left. 他说了那话就离开了。/ With daylight I hurried there to see what had happened. 天一亮我就去那儿看发生了什么事。10. (表同时或随同)与…一起，随着：The girl seemed to be growing prettier with each day. 那女孩好像长得一天比一天漂亮。11.(表伴随或附带情况)同时：I slept with the window open. 我开着窗户睡觉。/ Don’t speak with your mouth full. 不要满嘴巴食物说话。12.赞成，同意：I am with you there. 在那点上我同你意见一致。13.由…照看，交…管理，把…放在某处：I left a message for you with your secretary. 我给你留了个信儿交给你的秘书了。/ The keys are with reception. 钥匙放在接待处。14 (表连同或包含)连用，包含：The meal with wine came to ￡8 each. 那顿饭连酒每人8英镑。/ With preparation and marking a teacher works 12 hours a day. 一位老师连备课带批改作业每天工作12小时。15. (表对象或关系)对，关于，就…而言，对…来说：He is pleased with his new house. 他对他的新房子很满意。/ The teacher was very angry with him. 老师对他很生气。/ It’s the same with us students. 我们学生也是这样。16.(表对立或敌对)跟，以…为对手：The dog was fighting with the cat. 狗在同猫打架。/ He’s always arguing with his brother. 他老是跟他弟弟争论。17.(在祈使句中与副词连用)：Away with him! 带他走！/ Off with your clothes! 脱掉衣服！/ Down with your money! 交出钱来！ 【用法】1.表示方式、手段或工具等时(=以，用)，注意不要受汉语意思的影响而用错搭配，如“用英语”习惯上用in English，而不是with English。2.与某些抽象名词连用时，其作用相当于一个副词：with care=carefully 认真地/ with kindness=kindly 亲切地/ with joy=joyfully 高兴地/ with anger=angrily 生气地/ with sorrow=sorrowfully 悲伤地/ with ease=easily 容易地/ with delight=delightedly 高兴地/ with great fluency =very fluently 很流利地3.表示条件时，根据情况可与虚拟语气连用：With more money I would be able to buy it. 要是钱多一点，我就买得起了。/ With better equipment, we could have finished the job even sooner. 要是设备好些，我们完成这项工作还要快些。4.比较with 和as：两者均可表示“随着”，但前者是介词，后者是连词：He will improve as he grows older. 随着年龄的增长，他会进步的。/ People’s ideas change with the change of the times. 时代变了，人们的观念也会变化。5.介词with和to 均可表示“对”，但各自的搭配不同，注意不要受汉语意思的影响而用错，如在kind, polite, rude, good, married等形容词后通常不接介词with而接to。6.复合结构“with+宾语+宾语补足语”是一个很有用的结构，它在句中主要用作状语，表示伴随、原因、时间、条件、方式等；其中的宾语补足语可以是名词、形容词、副词、现在分词、过去分词、不定式、介词短语等：I went out with the windows open. 我外出时没有关窗户。/ He stood before his teacher with his head down. 他低着头站在老师面前。/ He was lying on the bed with all his clothes on. 他和衣躺在床上。/ He died with his daughter yet a schoolgirl. 他去世时，女儿还是个小学生。/ The old man sat there with a basket beside her. 老人坐在那儿，身边放着一个篮子。/ He fell asleep with the lamp burning. 他没熄灯就睡着了。/ He sat there with his eyes closed. 他闭目坐在那儿。/ I can’t go out with all these clothes to wash. 要洗这些衣服，我无法出去了。这类结构也常用于名词后作定语：The boy with nothing on is her son. 没穿衣服的这个男孩子是她儿子。 （摘自《英语常用词多用途词典》金盾出版社） - 1 -

精神分裂症应该怎么治疗

精神分裂症应该怎么治疗 1、坚持服药治疗 服药治疗是最有效的预防复发措施临床大量统计资料表明，大多数精神分裂症的复发与自行停药有关。坚持维持量服药的病人复发率为40%。而没坚持维持量服药者复发率高达80%。因此，病人和家属要高度重视维持治疗。 2、及时发现复发的先兆，及时处理 精神分裂症的复发是有先兆的，只要及时发现，及时调整药物和剂量，一般都能防止复发，常见的复发先兆为：病人无原因出现睡眠不好、懒散、不愿起床、发呆发愣、情绪不稳、无故发脾气、烦躁易怒、胡思乱想、说话离谱，或病中的想法又露头等。这时就应该及时就医，调整治疗病情波动时的及时处理可免于疾病的复发。 3、坚持定期门诊复查 一定要坚持定期到门诊复查，使医生连续地、动态地了解病情，使病人经常处于精神科医生的医疗监护之下，及时根据病情变化调整药量。通过复查也可使端正人及时得到咨询和心理治疗解除病人在生活、工作和药物治疗中的各种困惑，这对预防精神分裂症的复发也起着重要作用。 4、减少诱发因素 家属及周围人要充分认识到精神分裂症病人病后精神状态的薄弱性，帮助安排好日常的生活、工作、学习。经常与病人谈心，帮助病人正确对待疾病，正确对待现实生活，帮助病人提高心理承受能力，学会对待应激事件的方法，鼓励病人增强信心，指导病人充实生活，使病人在没有心理压力和精神困扰的环境中生活。 首先是性格上的改变，塬本活泼开朗爱玩的人，突然变得沉默寡言，独自发呆，不与人交往，爱干净的人也变的不注意卫生、生活

懒散、纪律松弛、做事注意力不集中，总是和患病之前的性格完全 相悖。 再者就是语言表达异常，在谈话中说一些无关的谈话内容，使人无法理解。连最简单的话语都无法准确称述，与之谈话完全感觉不 到重心。 第三个就是行为的异常，行为怪异让人无法理解，喜欢独处、不适意的追逐异性，不知廉耻，自语自笑、生活懒散、时常发呆、蒙 头大睡、四处乱跑，夜不归宿等。 还有情感上的变化，失去了以往的热情，开始变的冷淡、对亲人不关心、和友人疏远，对周围事情不感兴趣，一点消失都可大动干戈。 最后就是敏感多疑，对任何事情比较敏感，精神分裂症患者，总认为有人针对自己。甚至有时认为有人要害自己，从而不吃不喝。 但是也有的会出现难以入眠、容易被惊醒或睡眠不深，整晚做恶梦或者长睡不醒的现象。这些都有可能是患上了精神分裂症。 1.加强心理护理 心理护理是家庭护理中的重要方面，由于社会上普遍存在对精神病人的歧视和偏见，给病人造成很大的精神压力，常表现为自卑、 抑郁、绝望等，有的病人会因无法承受压力而自杀。家属应多给予 些爱心和理解，满足其心理需求，尽力消除病人的悲观情绪。病人 生活在家庭中，与亲人朝夕相处，接触密切，家属便于对病人的情感、行为进行细致的观察，病人的思想活动也易于向家属暴露。家 属应掌握适当的心理护理方法，随时对病人进行启发与帮助，启发 病人对病态的认识，帮助他们树立自信，以积极的心态好地回归社会。 2.重视服药的依从性 精神分裂症病人家庭护理的关键就在于要让病人按时按量吃药维持治疗。如果不按时服药，精神病尤其是精神分裂症的复发率很高。精神病人在医院经过一系统的治疗痊愈后，一般需要维持2~3年的