塑料模具畢業(yè)設(shè)計(jì)外文翻譯附英文原文.doc

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1、 長(zhǎng)江大學(xué)工程技術(shù)學(xué)院 畢業(yè)設(shè)計(jì)(論文) 外文翻譯 外文題目 A technical note on the characterization of electroformed nickel shells for their application to injection molds 譯文題目 一個(gè)描述電鑄鎳殼在注塑模具的應(yīng)用的技術(shù)研究 系部 機(jī) 械 系 專(zhuān)業(yè)班級(jí) 材控60901班 學(xué)生姓名 李小玲 指導(dǎo)教師 宋宏/高工 輔導(dǎo)教師 宋宏/高工 完成時(shí)間 2012年11月18日 一個(gè)描述電鑄鎳殼在注塑模具的應(yīng)用

2、的技術(shù)研究 ——Universidad de Las Palmas de Gran Canaria, Departamento de Ingenieria Mecanica, Spain 摘要： 在過(guò)去幾年中快速成型技術(shù)及快速模具已被廣泛開(kāi)發(fā)利用. 在本文中,使用電芯作為核心程序?qū)λ芰献⑸淠＞叻治? 通過(guò)差分系統(tǒng)快速成型制造外殼模型. 主要目的是分析電鑄鎳殼力學(xué)特征、 研究相關(guān)金相組織,硬度,內(nèi)部壓力等不同方面，由這些特征參數(shù)以生產(chǎn)電鑄設(shè)備的外殼. 最后一個(gè)核心是檢驗(yàn)注塑模具. 關(guān)鍵詞：電鍍；電鑄；微觀結(jié)構(gòu)；鎳 1. 引言

3、 現(xiàn)代工業(yè)遇到很大的挑戰(zhàn)，其中最重要的是怎么樣提供更好的產(chǎn)品給消費(fèi)者,更多種類(lèi)和更新?lián)Q代問(wèn)題. 因此,現(xiàn)代工業(yè)必定產(chǎn)生更多的競(jìng)爭(zhēng)性. 毫無(wú)疑問(wèn),結(jié)合時(shí)間變量和質(zhì)量變量并不容易,因?yàn)樗麄兘?jīng)常彼此互為條件; 先進(jìn)的生產(chǎn)系統(tǒng)將允許該組合以更加有效可行的方式進(jìn)行，例如,如果是觀測(cè)注塑系統(tǒng)的轉(zhuǎn)變、 我們得出的結(jié)論是,事實(shí)上 一個(gè)新產(chǎn)品在市場(chǎng)上具有較好的質(zhì)量它需要越來(lái)越少的時(shí)間 快速模具制造技術(shù)是在這一領(lǐng)域, 中可以改善設(shè)計(jì)和制造注入部分的技術(shù)進(jìn)步. 快速模具制造技術(shù)基本上是一個(gè)中小型系列的收集程序，在很短的時(shí)間內(nèi)在可接受的精度水平基礎(chǔ)上讓我們獲得模具的塑料部件。其應(yīng)用不僅在更加廣闊而且生產(chǎn)也不斷增

4、多。 本文包括了很廣泛的研究路線(xiàn),在這些研究路線(xiàn)中我們可以嘗試去學(xué)習(xí)，定義，分析，測(cè)試，提出在工業(yè)水平方面的可行性，從核心的注塑模具制造獲取電鑄鎳殼，同時(shí)作為一個(gè)初始模型的原型在一個(gè)FDM設(shè)備上的快速成型。 不得不說(shuō)的是,先進(jìn)的電鑄技術(shù)應(yīng)用在無(wú)數(shù)的行業(yè)，但這一研究工作調(diào)查到什么程度,并根據(jù)這些參數(shù),使用這種技術(shù)生產(chǎn)快速模具在技術(shù)上是可行的. 都產(chǎn)生一個(gè)準(zhǔn)確的，系統(tǒng)化使用的方法以及建議的工作方法. 2 制造過(guò)程的注塑模具 薄鎳外殼的核心是電鑄,獲得一個(gè)充滿(mǎn)epoxic金屬樹(shù)脂的一體化的核心板塊模具(圖1)允許直接制造注射型多用標(biāo)本，因?yàn)樗鼈兇_定了新英格蘭大學(xué)英文國(guó)際表卓

5、華組織3167標(biāo)準(zhǔn)。這樣做的目的是確定力學(xué)性能的材料收集代表行業(yè)。 該階段取得的核心[4]，根據(jù)這一方法研究了這項(xiàng)工作,有如下: a,用CAD系統(tǒng)設(shè)計(jì)的理想對(duì)象 b模型制造的快速成型設(shè)備(頻分多路系統(tǒng)). 所用材料將是一個(gè)ABS塑料 c一個(gè)制造的電鑄鎳殼，已事先涂有導(dǎo)電涂料(必須有導(dǎo)電). d無(wú)外殼模型 e核心的生產(chǎn)是背面外殼環(huán)氧樹(shù)脂的抗高溫與具有制冷的銅管管道. 有兩個(gè)腔的注塑模具、 其中一個(gè)是電核心和其他直接加工的移動(dòng)版. 因此,在同一工藝條件下，同時(shí)注入兩個(gè)標(biāo)準(zhǔn)技術(shù)制造，獲得相同的工作。 3 獲得電殼:設(shè)備 電鍍是電解質(zhì)時(shí)電流的化學(xué)變化,電解所形成的

6、直流電有兩個(gè)電極，陽(yáng)極和陰極。當(dāng)電流流經(jīng)電路，在離子溶液中轉(zhuǎn)化為原子。 電鍍液用于這項(xiàng)工作是由氨基磺酸鎳400 毫升/升,氯化鎳(10克/升)、硼酸(50克/升),allbrite SLA(30毫升/升),allbrite703(2毫升/升). 選擇這種組合主要原因是我們考慮注塑模具程序是玻璃纖維. 氨基磺酸鎳讓我們獲得可以接受的內(nèi)部壓力(測(cè)試不同工藝條件結(jié)果,而不是最佳工藝條件約2兆帕最高為50兆帕). 不過(guò),這種內(nèi)部壓力是由touenesulfonamode衍生物和甲醛水溶液使用的ALLbrite添加劑的結(jié)果。 這種添加劑也增加了殼的阻力. Allbrite703是一種可生物降解水溶液

7、表使用劑 氯化鎳,有利于解決金屬統(tǒng)一分布在陰極，提高導(dǎo)電性的問(wèn)題。硼酸作為PH值緩沖區(qū)。 該設(shè)備用于制造殼的測(cè)試如下： ● 聚丙烯:600毫米400毫米500毫米的尺寸 ● 三聚四氟乙烯電阻器,每一個(gè)有800W ● 具有機(jī)械攪拌系統(tǒng)的陰極 ●循環(huán)和過(guò)濾系統(tǒng)用的泵和聚丙烯過(guò)濾器。 ● 充電整流器. 最大強(qiáng)度在連續(xù)50個(gè)A和連續(xù)電流電壓介于0至16伏 ● 籃鈦鎳陽(yáng)極(鎳硫回合電解鎳)純度99%以上 ● 氣體注入系統(tǒng) 一旦電流密度( 1-22A/dm）,溫度(35至55℃)和pH值,已經(jīng)確定，執(zhí)行參數(shù)以及測(cè)試的進(jìn)程部分不可改變。 4 獲得硬度 電殼硬度的測(cè)試一直保持在相當(dāng)高的很

8、穩(wěn)定的結(jié)果。如圖2，可以看到：電流密度值2.5到22A/dm，硬度值介于540到580高壓，PH值為4+-0.2和溫度為45攝氏度，如果PH減少到3.5和溫度為55攝氏度，硬度為520以上，高壓低于560.這一測(cè)試使常規(guī)組成不同于其他氨基磺酸鎳，允許其經(jīng)營(yíng)更加廣泛，然而，這種operatyivity將是一定的取決于其他因素，如內(nèi)部壓力，因?yàn)樗赡艿淖儺悺? 改變PH值，電流密度和溫度等，另一方面，傳統(tǒng)的硬度氨基磺酸鎳承受的高壓在200-250之間，遠(yuǎn)低于取得的一個(gè)實(shí)驗(yàn)結(jié)果的電壓。對(duì)于一個(gè)注塑模具，硬度可以接受的起點(diǎn)300高壓這是必須考慮的，注塑模具中最常見(jiàn)的材料，有改善鋼（290高壓），整體淬

9、火（520-595高壓），casehardened鋼鐵（760-8--高壓）等，以這樣一種方式，可以看到，注塑模具硬度水平的鎳是殼內(nèi)的高范圍的材料。因?yàn)檫@是一個(gè)負(fù)責(zé)內(nèi)部壓力的塑料注射液，這種方式與環(huán)氧樹(shù)脂灌漿將遵循它，相反對(duì)低韌性的殼補(bǔ)償，這就是為什么它是必定盡可能的外殼厚度均勻，并沒(méi)有重要的原因，如 腐蝕。 5 金相組織 為了分析金相結(jié)構(gòu)、電流密度、溫度主要變化. 在正面橫向部分（垂直沉積）對(duì)樣品進(jìn)行了分析，為了方便地封裝在樹(shù)脂，拋光。銘刻，在不同階段的混合乙酸和硝酸。該時(shí)刻間隔15,25,40,50之后再次拋光, 為了在金相顯微鏡下觀察奧林巴斯PME3-ADL3.3X/10X

10、 必須要說(shuō)的是，這一條規(guī)定顯示了圖片之后的評(píng)論，用于制造該模型的殼在FDM快速成型機(jī)里融化的塑料材料（澳大利亞統(tǒng)計(jì)局）鞏固和解決了該階層。后來(lái)在每一個(gè)層，擠出的模具都留下一個(gè)大約0.15毫米直徑橫向和縱向的線(xiàn)程。因此，在表面可以看到細(xì)線(xiàn)表面頭部的機(jī)器。這些西路將作為參考信息解決鎳的重復(fù)性問(wèn)題。重復(fù)性的模型將作為一個(gè)基本要素來(lái)評(píng)估注塑模具的表面紋理。 表1測(cè)試系列： 表1. 檢驗(yàn)系列 系列 pH 溫度(℃) 電流密度A/mm2 1 4.20.2 55 2.22 2 3.90.2 45 5.56 3 4.00.2 45 10.00 4 4

11、.00.2 45 22.22 圖3說(shuō)明該系列第一時(shí)刻表面的樣本 它顯示了流道起點(diǎn)的頻率復(fù)用機(jī)，這就是說(shuō)，又一個(gè)很好的重復(fù)性。它不能仍然要注意四舍五入結(jié)構(gòu)。在圖4 系列2，經(jīng)過(guò)第二次，可以看到一條線(xiàn)的流道的方式與以前的相比不太清楚。在圖5系列3雖然第二次時(shí)刻開(kāi)始出現(xiàn)圓形晶結(jié)果是非常困難的。此外，最黑暗的部分表明時(shí)刻不足的進(jìn)程和組成。 這種現(xiàn)象表明，在低電流密度和高溫條件下工作，得到更小的晶粒尺寸和殼重現(xiàn)性好，就是所需要的足夠的應(yīng)用程序。 如果分析橫向平面進(jìn)行的沉積，可以在所有測(cè)試樣品和條件增長(zhǎng)的結(jié)構(gòu)層（圖6），犧牲一個(gè)低延展性取得令人滿(mǎn)意的高機(jī)械阻力，最重要的是添加劑

12、的使用情況，氨基磺酸鎳液的添加劑通常創(chuàng)建一個(gè)纖維和非層狀結(jié)果[9].這個(gè)問(wèn)題表明在任何情況下改變潤(rùn)濕劑，由于該層結(jié)構(gòu)的決定因素是這種結(jié)構(gòu)的應(yīng)力減速器（ALLbriteSLA)。另一方面，她也是測(cè)試的層狀結(jié)構(gòu)不同厚度中的電流密度. 6 內(nèi)部壓力 殼的一個(gè)主要特點(diǎn)是應(yīng)該有其應(yīng)用，如插入時(shí)要有一個(gè)低水平的內(nèi)部壓力。測(cè)試不同的溫度很電流密度，所采取的措施取決于陰極彎曲張力計(jì)法。A鋼測(cè)試控制使用側(cè)固定和其他自由度固定（160毫米長(zhǎng)，12.7毫米寬，0.3毫米厚）。金屬沉積只有在控制了機(jī)械拉伸力（拉深或壓應(yīng)力），才能計(jì)算內(nèi)部壓力。彈性的角度來(lái)看，斯托尼模型應(yīng)用，假定鎳基質(zhì)厚度

13、，對(duì)部分鋼材產(chǎn)生足夠?。?微米）的影響。在所有測(cè)試情況下，一個(gè)能夠接受的應(yīng)用程序在內(nèi)部壓力在50兆帕的極端條件下和2兆帕的最佳條件下產(chǎn)生。得出的結(jié)論是，內(nèi)部壓力在不同的工作條件和參數(shù)沒(méi)有明顯的變化條件下。 7 校驗(yàn)注塑模具 試驗(yàn)已進(jìn)行了各種代表性熱塑性材料如聚丙烯、高密度聚乙烯和PC、 并進(jìn)行了注射部件性能的分析，如尺寸，重量，阻力，剛度和柔性。對(duì)殼的力學(xué)性能進(jìn)行了拉伸破壞性測(cè)試和分析。大約500個(gè)注射液在其余的條件下，進(jìn)行了更多的檢驗(yàn) 總體而言, 為分析一種材料，重要的是注意到行為標(biāo)本中的核心和那些加工腔之間的差異。然而在分析光彈注入標(biāo)本（圖7）有人注意到不同的國(guó)家之間張力存在兩種不同

14、的類(lèi)型的標(biāo)本，是由于不同的模腔熱傳遞和剛度。這種差異解釋了柔性的變化更加突出的部分晶體材料，如聚乙烯和聚酰胺6. 有人注意到一個(gè)較低的柔性標(biāo)本在的高密度聚乙烯分析測(cè)試管在鎳核心的情況下，量化30%左右。如尼龍6這個(gè)值也接近50%。 8 結(jié)論 經(jīng)過(guò)連續(xù)的測(cè)試，注塑模具在不同條件下檢查的氨基磺酸鎳液使用添加劑。這就是說(shuō)塑性好，硬度好和摩擦力好的層狀結(jié)構(gòu)，已取得的力學(xué)性能是可以接受的。借鞋缺陷的鎳殼將部分取代環(huán)氧樹(shù)脂為核心的注塑模具，使注入的一系列中型塑料零部件達(dá)到可接受的質(zhì)量的水平。 外 文 出 處:

15、 參考資料 [1] A.E.W. Rennie, C.E. Bocking and G.R. Bennet, Electroforming of rapid prototyping mandrels for electro discharge machining electrodes, J. Mater. Process. Technol. 110 (2001), pp. 186–196. [2] P.K.D.V. Yarlagadda, I.P. Ilyas and P. Chrstodoulou, Development of rapid tooling for sheet met

16、al drawing using nickel electroforming and stereo lithography processes, J. Mater. Process. Technol. 111 (2001), pp. 286–294. [3] J. Hart, A. Watson, Electroforming: A largely unrecognised but expanding vital industry, Interfinish 96, 14 World Congress, Birmingham, UK, 1996. [4] M. Monzn et al.,

17、 Aplicacin del electroconformado en la fabricacin rpida de moldes de inyeccin, Revista de Plsticos Modernos. 84 (2002), p. 557. [5] L.F. Hamilton et al., Clculos de Qumica Analtica, McGraw Hill (1989). [6] E. Julve, Electrodeposicin de metales, 2000 (E.J.S.). [7] A. Watson, Nickel Sulphamate S

18、olutions, Nickel Development Institute (1989). [8] A. Watson, Additions to Sulphamate Nickel Solutions, Nickel Development Institute (1989). [9] J. Dini, Electrodeposition Materials Science of Coating and Substrates, Noyes Publications (1993). [10] J.W. Judy, Magnetic microactuators with polys

19、ilicon flexures, Masters Report, Department of EECS, University of California, Berkeley, 1994. (cap′. 3). A technical note on the characterization of electroformed nickel shells for their application to injection molds ——aUniversidad de Las Palmas de Gran Canaria, Departamento

20、de Ingenieria Mecanica, Spain Abstract The techniques of rapid prototyping and rapid tooling have been widely developed during the last years. In this article, electroforming as a procedure to make cores for plastics injection molds is analysed. Shells are obtained from models manufactured th

21、rough rapid prototyping using the FDM system. The main objective is to analyze the mechanical features of electroformed nickel shells, studying different aspects related to their metallographic structure, hardness, internal stresses and possible failures, by relating these features to the parameters

22、 of production of the shells with an electroforming equipment. Finally a core was tested in an injection mold. Keywords: Electroplating; Electroforming; Microstructure; Nickel 1. Introduction One of the most important challenges with which modern industry comes across is to offer the consumer

23、 better products with outstanding variety and time variability (new designs). For this reason, modern industry must be more and more competitive and it has to produce with acceptable costs. There is no doubt that combining the time variable and the quality variable is not easy because they frequentl

24、y condition one another; the technological advances in the productive systems are going to permit that combination to be more efficient and feasible in a way that, for example, if it is observed the evolution of the systems and techniques of plastics injection, we arrive at the conclusion that, in f

25、act, it takes less and less time to put a new product on the market and with higher levels of quality. The manufacturing technology of rapid tooling is, in this field, one of those technological advances that makes possible the improvements in the processes of designing and manufacturing injected pa

26、rts. Rapid tooling techniques are basically composed of a collection of procedures that are going to allow us to obtain a mold of plastic parts, in small or medium series, in a short period of time and with acceptable accuracy levels. Their application is not only included in the field of making pla

27、stic injected pieces [1], [2] and [3], however, it is true that it is where they have developed more and where they find the highest output. This paper is included within a wider research line where it attempts to study, define, analyze, test and propose, at an industrial level, the possibility of

28、 creating cores for injection molds starting from obtaining electroformed nickel shells, taking as an initial model a prototype made in a FDM rapid prototyping equipment. It also would have to say beforehand that the electroforming technique is not something new because its applications in the ind

29、ustry are countless [3], but this research work has tried to investigate to what extent and under which parameters the use of this technique in the production of rapid molds is technically feasible. All made in an accurate and systematized way of use and proposing a working method. 2. Manufa

30、cturing process of an injection mold The core is formed by a thin nickel shell that is obtained through the electroforming process, and that is filled with an epoxic resin with metallic charge during the integration in the core plate [4] This mold (Fig. 1) permits the direct manufacturing by inject

31、ion of a type a multiple use specimen, as they are defined by the UNE-EN ISO 3167 standard. The purpose of this specimen is to determine the mechanical properties of a collection of materials representative industry, injected in these tools and its coMParison with the properties obtained by conventi

32、onal tools. Fig. 1.Manufactured injection mold with electroformed core. The stages to obtain a core [4], according to the methodology researched in this work, are the following: (a) Design in CAD system of the desired object. (b) Model manufacturing in a rapid prototyping equipment (FDM

33、system). The material used will be an ABS plastic. (c) Manufacturing of a nickel electroformed shell starting from the previous model that has been coated with a conductive paint beforehand (it must have electrical conductivity). (d) Removal of the shell from the model. (e) Production of the core

34、 by filling the back of the shell with epoxy resin resistant to high temperatures and with the refrigerating ducts made with copper tubes. The injection mold had two cavities, one of them was the electroformed core and the other was directly machined in the moving platen. Thus, it was obtained, wit

35、h the same tool and in the same process conditions, to inject simultaneously two specimens in cavities manufactured with different technologies. 3. Obtaining an electroformed shell: the equipment Electrodeposition [5] and [6] is an electrochemical process in which a chemical change has its origin

36、 within an electrolyte when passing an electric current through it. The electrolytic bath is formed by metal salts with two submerged electrodes, an anode (nickel) and a cathode (model), through which it is made to pass an intensity coming from a DC current. When the current flows through the circui

37、t, the metal ions present in the solution are transformed into atoms that are settled on the cathode creating a more or less uniform deposit layer. The plating bath used in this work is formed by nickel sulfamate [7] and [8] at a concentration of 400ml/l, nickel chloride (10g/l), boric acid (50g/l

38、), Allbrite SLA (30cc/l) and Allbrite 703 (2cc/l). The selection of this composition is mainly due to the type of application we intend, that is to say, injection molds, even when the injection is made with fibreglass. Nickel sulfamate allows us to obtain an acceptable level of internal stresses in

39、the shell (the tests gave results, for different process conditions, not superior to 50MPa and for optimum conditions around 2MPa). Nevertheless, such level of internal pressure is also a consequence of using as an additive Allbrite SLA, which is a stress reducer constituted by derivatives of toluen

40、esulfonamide and by formaldehyde in aqueous solution. Such additive also favours the increase of the resistance of the shell when permitting a smaller grain. Allbrite 703 is an aqueous solution of biodegradable surface-acting agents that has been utilized to reduce the risk of pitting. Nickel chlori

41、de, in spite of being harmful for the internal stresses, is added to enhance the conductivity of the solution and to favour the uniformity in the metallic distribution in the cathode. The boric acid acts as a pH buffer. The equipment used to manufacture the nickel shells tested has been as follows

42、: ? Polypropylene tank: 600mm400mm500mm in size. ? Three teflon resistors, each one with 800W. ? Mechanical stirring system of the cathode. ? System for recirculation and filtration of the bath formed by a pump and a polypropylene filter. ? Charging rectifier. Maximum intensity in continuous 5

43、0A and continuous current voltage between 0 and 16V. ? Titanium basket with nickel anodes (Inco S-Rounds Electrolytic Nickel) with a purity of 99%. ? Gases aspiration system. Once the bath has been defined, the operative parameters that have been altered for testing different conditions of the pr

44、ocess have been the current density (between 1 and 22A/dm2), the temperature (between 35 and 55C) and the pH, partially modifying the bath composition. 4. Obtained hardness One of the most interesting conclusions obtained during the tests has been that the level of hardness of the different elect

45、roformed shells has remained at rather high and stable values. In Fig. 2, it can be observed the way in which for current density values between 2.5 and 22A/dm2, the hardness values range from 540 and 580HV, at pH 40.2 and with a temperature of 45C. If the pH of the bath is reduced at 3.5 and the te

46、mperature is 55C those values are above 520HV and below 560HV. This feature makes the tested bath different from other conventional ones composed by nickel sulfamate, allowing to operate with a wider range of values; nevertheless, such operativity will be limited depending on other factors, such as

47、internal stress because its variability may condition the work at certain values of pH, current density or temperature. On the other hand, the hardness of a conventional sulfamate bath is between 200–250HV, much lower than the one obtained in the tests. It is necessary to take into account that, for

48、 an injection mold, the hardness is acceptable starting from 300HV. Among the most usual materials for injection molds it is possible to find steel for improvement (290HV), steel for integral hardening (520–595HV), casehardened steel (760–800HV), etc., in such a way that it can be observed that the

49、hardness levels of the nickel shells would be within the medium–high range of the materials for injection molds. The objection to the low ductility of the shell is compensated in such a way with the epoxy resin filling that would follow it because this is the one responsible for holding inwardly the

50、 pressure charges of the processes of plastics injection; this is the reason why it is necessary for the shell to have a thickness as homogeneous as possible (above a minimum value) and with absence of important failures such as pitting. Fig. 2.Hardness variation with current density. pH 40.2,

51、 T=45C. 5. Metallographic structure In order to analyze the metallographic structure, the values of current density and temperature were mainly modified. The samples were analyzed in frontal section and in transversal section (perpendicular to the deposition). For achieving a convenient preparat

52、ion, they were conveniently encapsulated in resin, polished and etched in different stages with a mixture of acetic acid and nitric acid. The etches are carried out at intervals of 15, 25, 40 and 50s, after being polished again, in order to be observed afterwards in a metallographic microscope Olymp

53、us PME3-ADL 3.3/10. Before going on to comment the photographs shown in this article, it is necessary to say that the models used to manufacture the shells were made in a FDM rapid prototyping machine where the molten plastic material (ABS), that later solidifies, is settled layer by layer. In eac

54、h layer, the extruder die leaves a thread approximately 0.15mm in diameter which is compacted horizontal and vertically with the thread settled inmediately after. Thus, in the surface it can be observed thin lines that indicate the roads followed by the head of the machine. These lines are going to

55、act as a reference to indicate the reproducibility level of the nickel settled. The reproducibility of the model is going to be a fundamental element to evaluate a basic aspect of injection molds: the surface texture. The tested series are indicated in Table 1. Table 1. Tested series Series

56、 pH Temperature (C) Current density (A/dm2) 1 4.20.2 55 2.22 2 3.90.2 45 5.56 3 4.00.2 45 10.00 4 4.00.2 45 22.22 Fig. 3 illustrates the surface of a sample of the series after the first etch. It shows the roads originated by the FDM machine, that is to say that ther

57、e is a good reproducibility. It cannot be still noticed the rounded grain structure. In Fig. 4, series 2, after a second etch, it can be observed a line of the road in a way less clear than in the previous case. In Fig. 5, series 3 and 2 etch it begins to appear the rounded grain structure although

58、it is very difficult to check the roads at this time. Besides, the most darkened areas indicate the presence of pitting by inadequate conditions of process and bath composition. Fig. 3.Series 1 (150), etch 1. Fig. 4.Series 2 (300), etch 2. Fig. 5.Series 3 (300), etch 2. This b

59、ehavior indicates that, working at a low current density and a high t matter demonstrated that the determinant for such structure was the stress reducer (Allbrite SLA). On the other hand, it was also tested that the laminar structure varies according to the thickness of the layer in terms of the cur

60、rent density. Fig. 6.Plane transversal of series 2 (600), etch 2. 6. Internal stresses One of the main characteristic that a shell should have for its application like an insert is to have a low level of internal stresses. Different tests at different bath temperatures and current densities were done and a measure system rested on cathode flexural tensiometer method was used. A steel testing control was used with a side fixed and the other free