南博, 臧佳棟, 陸文龍, 楊廷旺, 張升偉, 張海波

增材制造壓電陶瓷研究進(jìn)展

南博1,2, 臧佳棟3, 陸文龍3, 楊廷旺3, 張升偉3, 張海波1,2

(1. 華中科技大學(xué) 材料科學(xué)與工程學(xué)院, 材料成形與模具技術(shù)國(guó)家重點(diǎn)實(shí)驗(yàn)室, 武漢 430074; 2. 廣東華中科技大學(xué)工業(yè)技術(shù)研究院, 東莞 523808; 3. 深圳市基克納科技有限公司, 深圳 518100)

壓電陶瓷是一種可以實(shí)現(xiàn)機(jī)械信號(hào)和電信號(hào)相互轉(zhuǎn)換的功能陶瓷。由壓電陶瓷與有機(jī)相構(gòu)成的復(fù)合材料具有不同的宏觀連接方式, 這不僅決定了壓電器件廣泛的應(yīng)用場(chǎng)合, 而且推動(dòng)了壓電陶瓷材料和器件多樣化的成型技術(shù)發(fā)展。與傳統(tǒng)成型技術(shù)相比, 增材制造技術(shù)的最大優(yōu)勢(shì)在于無(wú)需模具即可實(shí)現(xiàn)外形復(fù)雜的小批量樣品快速成型, 這與多樣化的壓電陶瓷及其器件研發(fā)需求十分契合, 同時(shí)因其樣品后續(xù)加工量少、原材料利用率高、無(wú)需切削液的特點(diǎn), 得到了學(xué)術(shù)界和工業(yè)界的廣泛關(guān)注。在陶瓷材料增材制造領(lǐng)域, 功能陶瓷和器件的研究仍在增長(zhǎng)期。本文從不同增材制造技術(shù)角度, 探討和對(duì)比現(xiàn)階段無(wú)鉛和含鉛壓電陶瓷增材制造的發(fā)展歷史、原料制備、外形設(shè)計(jì)、功能特性檢測(cè)及試樣的應(yīng)用, 并根據(jù)現(xiàn)階段各增材制造技術(shù)的優(yōu)、劣勢(shì)對(duì)其未來(lái)進(jìn)行了展望。

增材制造; 含鉛壓電陶瓷; 無(wú)鉛壓電陶瓷; 功能特性; 綜述

壓電陶瓷是一種廣泛應(yīng)用于微電子、汽車、自動(dòng)化、醫(yī)療影像、軍事等領(lǐng)域的電子陶瓷[1-7]。目前, 商業(yè)化的壓電陶瓷以含鉛體系為主, 具有良好的綜合性能。然而, 鉛對(duì)環(huán)境有害且不可生物降解, 會(huì)隨著水循環(huán)和大氣循環(huán)進(jìn)入人體[8-9]。近年來(lái), 制備可替代含鉛體系的無(wú)鉛壓電陶瓷和器件成為學(xué)術(shù)界和工業(yè)界的重要議題。

壓電陶瓷的材料成分固然重要, 在很大程度上決定了其功能性能, 然而壓電陶瓷在某一領(lǐng)域的應(yīng)用還由壓電陶瓷的宏觀連接方式(Con-nectivity)決定。連接方式的概念于1978年由Newnham等[10]提出, 當(dāng)時(shí)科學(xué)家正在設(shè)計(jì)適當(dāng)?shù)膲弘娞沾蓚鞲衅鹘Y(jié)構(gòu), 以提高由陶瓷和高分子材料組成的復(fù)合材料的品質(zhì)因數(shù), 最大程度發(fā)揮二者的壓電特性和柔性, 提出了連接方式的概念。對(duì)于由兩相構(gòu)成的復(fù)合物, 連接方式共有10種, 即0-0、1-0、2-0、3-0、1-1、2-1、3-1、2-2、3-2和3-3, 如圖1(a)所示。多樣化的連接方式也推動(dòng)了成型技術(shù)的發(fā)展。例如, 針對(duì)2-2連接方式(用于電容、儲(chǔ)能、壓電懸臂梁等), 壓電陶瓷膜的膜厚逐漸變薄, 這為流延成型[11]、旋轉(zhuǎn)涂布[12]的研究帶來(lái)機(jī)遇; 針對(duì)1-3連接方式(用于超聲換能器、聲吶等), 不同精度呈陣列狀分布的壓電陶瓷可以通過(guò)機(jī)械切削[13]、凝膠注模[14]、噴墨打印[15]等技術(shù)制備。成型技術(shù)是連接壓電陶瓷和壓電器件的紐帶。

增材制造(Additive Manufacturing, AM)近年來(lái)受到廣泛關(guān)注。目前, 高分子材料增材制造技術(shù)已逐漸成熟, 金屬增材制造生產(chǎn)的零部件也已進(jìn)入汽車行業(yè)[16-17], 而陶瓷和玻璃的增材制造技術(shù)發(fā)展緩慢, 仍未實(shí)現(xiàn)產(chǎn)業(yè)化應(yīng)用。這是由陶瓷和玻璃材料的本征特性決定的: 一是因?yàn)樘沾扇埸c(diǎn)高, 導(dǎo)熱性能遜于金屬, 難以使用激光熔融技術(shù)進(jìn)行成型加工; 二是因?yàn)樘沾珊筒ＡС厮苄?、韌性差, 必須借助高分子聚合物提高可塑性, 進(jìn)而改善其可加工性能。表1列舉了目前常用的陶瓷材料增材制造技術(shù)的優(yōu)缺點(diǎn)和原材料成分。與傳統(tǒng)加工方式不同, 每種增材制造技術(shù)都有難點(diǎn)和優(yōu)勢(shì)。粉末床需要的原料量大、成本高, 而壓電陶瓷粉末的材料種類多、可購(gòu)買的標(biāo)準(zhǔn)牌號(hào)有限, 不適合實(shí)驗(yàn)室研究, 這也是粉末床類壓電陶瓷增材制造報(bào)道較少的原因之一。無(wú)論光固化還是直寫(xiě)式等需要漿料的增材制造技術(shù), 都具有原料用量少, 粉末的理化性能和漿料的固含量、均勻性可調(diào)的優(yōu)點(diǎn), 故目前報(bào)道較多。圖1(b～f)為常用壓電陶瓷增材制造的設(shè)備示意圖。目前, 壓電陶瓷增材制造的文獻(xiàn)主要集中在成型工藝參數(shù)和功能性能的檢測(cè), 偶見(jiàn)與器件相關(guān)的報(bào)道。本文從不同增材制造技術(shù)角度闡述壓電陶瓷增材制造的歷史、材料體系、功能性能及應(yīng)用場(chǎng)景, 并對(duì)其未來(lái)可能的研究方向進(jìn)行展望。

圖1 壓電陶瓷的連接方式與常用于壓電陶瓷的增材制造技術(shù)示意圖

(a) 10 types of connectivitities in bi-phase composites[10]; (b) Vat photopolymerization[18]; (c) Direct ink writing[21]; (d) Inkjet printing[23]; (e) Fused deposition modelling[26]; (f) Binder jetting[29]

表1 陶瓷增材制造技術(shù)的優(yōu)缺點(diǎn)和原材料成分對(duì)比

1 光固化成型

光固化技術(shù)可追溯至18世紀(jì), 而現(xiàn)代光固化技術(shù)與增材制造的結(jié)合起源于20世紀(jì)70年代[30]。1971年, Swainson[31]提出用兩束相交的放射性光線在材料中引發(fā)高分子聚合物交聯(lián)或者降解建立三維物體。由于當(dāng)時(shí)設(shè)備的限制, 該方法的制備精度低而被迫中止。之后, Hull等[32-33]在此基礎(chǔ)上建立了現(xiàn)代光固化成型技術(shù)的構(gòu)想, 即逐層曝光固化成型三維物體。隨著高分子和曝光技術(shù)的發(fā)展, 在光敏高分子材料中添加陶瓷粉末制備可光固化的陶瓷漿料, 實(shí)現(xiàn)陶瓷材料的光固化成型。近年來(lái), 光敏陶瓷前驅(qū)體與光固化技術(shù)結(jié)合, 成為光固化陶瓷增材制造的重要研究方向之一[34-35]。

壓電陶瓷立體光固化技術(shù)成型始于本世紀(jì)初。法國(guó)研究人員[36-38]率先報(bào)道了PZT的制作過(guò)程, 他們從配制光固化漿料入手, 詳細(xì)闡述了黏結(jié)劑、固含量、表面活性劑等因素對(duì)漿料流變學(xué)的影響, 結(jié)合曝光固化工藝闡述生坯制備工藝, 并在此基礎(chǔ)上對(duì)試樣的小型化進(jìn)行了探討。隨著壓電陶瓷的無(wú)鉛化趨勢(shì), 研究人員開(kāi)始運(yùn)用立體光固化技術(shù)制備無(wú)鉛壓電陶瓷。Kim等[39]運(yùn)用水熱反應(yīng)制備BaTiO3(BT)納米粉末, 表面修飾后與聚乙二醇二丙烯酸酯和2,2-二羥甲基丙酸混合, 通過(guò)控制光輻射功率、單體濃度、光引發(fā)劑濃度和粉末固含量, 對(duì)打印工藝進(jìn)行優(yōu)化, 實(shí)現(xiàn)快速(<2 s)打印。然后他們利用不同形狀的掩模, 制備了BT的點(diǎn)陣列、正方形陣列和蜂窩狀陣列, 如圖2所示。Chen等[40]采用丁酮(體積分?jǐn)?shù)66%)和乙醇(體積分?jǐn)?shù)34%)混合溶劑作為分散體系, 將BT粉末和分散劑與之混合, 對(duì)BT粉末進(jìn)行表面修飾。經(jīng)表面修飾的BT粉末和光敏樹(shù)脂混合得到光敏漿料, 用以制備柱狀陣列的樣品。經(jīng)1330 ℃燒結(jié)的樣品進(jìn)行介電測(cè)試, 在1 kHz頻率下的介電常數(shù)(r)為1300, 介電損耗(tan)僅為0.012。在100 ℃、電場(chǎng)30 kV/cm極化30 min后, 壓電常數(shù)33為160 pC/N。將光固化技術(shù)制備的BT試樣性能與傳統(tǒng)固相反應(yīng)法制備的BT性能(介電常數(shù)為1700, 介電損耗<0.1, 壓電常數(shù)33為190 pC/N)進(jìn)行對(duì)比發(fā)現(xiàn)[41], 兩種技術(shù)制備的BT性能相近。之后, Song等[19]在文獻(xiàn)[40]的工作基礎(chǔ)上, 對(duì)立體光固化技術(shù)制得的試樣封裝制成超聲傳感器。經(jīng)過(guò)測(cè)試, 在2.35～2.8 μs范圍內(nèi)可以清晰地看到強(qiáng)度為(0.11±0.055) V的回聲響應(yīng), 這說(shuō)明超聲傳感器可以有效地實(shí)現(xiàn)超聲信號(hào)和電信號(hào)轉(zhuǎn)換。除了BT基壓電陶瓷, 立體光固化技術(shù)還應(yīng)用于無(wú)鉛壓電陶瓷KNaNbO3(KNN)的制備。Chen等[42]通過(guò)微型立體光固化技術(shù)(Micro-stereolithography)制備KNN環(huán)形陣列, 樣品居里溫度為230 ℃, 介電常數(shù)為 2150, 介電損耗為0.08, 在室溫、電場(chǎng)3 kV/mm條件下對(duì)樣品進(jìn)行極化, 壓電常數(shù)33為170 pC/N。這與傳統(tǒng)固相反應(yīng)法制得的KNN(居里溫度為230 ℃, 壓電常數(shù)33為300 pC/N)相比[43], 性能略有下降。在結(jié)構(gòu)設(shè)計(jì)方面, Cui等[44]利用立體光固化技術(shù)實(shí)現(xiàn)高固含量漿料成型, 同時(shí)將超材料對(duì)三維結(jié)構(gòu)的節(jié)點(diǎn)單元應(yīng)用在壓電陶瓷微觀設(shè)計(jì)上(如圖3所示), 使樣品在微觀上獲得更多可能性的連接方式。通過(guò)高精度的微納結(jié)構(gòu)設(shè)計(jì)結(jié)構(gòu)單元, 實(shí)現(xiàn)材料高自由度設(shè)計(jì)的機(jī)電耦合各向異性和順向效應(yīng), 這為今后觸覺(jué)傳感、源頭檢測(cè)、聲學(xué)傳感等壓電器件指明了研究方向。

圖2 不同形狀的壓電陶瓷BT陣列[39]

(a) Dot array; (b, c) Square arrays with different sized void spaces; (d) Honeycomb array

圖3 可調(diào)節(jié)壓電常數(shù)的壓電超材料設(shè)計(jì)[44]

除了無(wú)鉛壓電陶瓷成型, 立體光固化技術(shù)還可用于制備含鉛壓電超聲傳感器。Chen等[45]運(yùn)用立體光固化技術(shù)將不同固含量的漿料(質(zhì)量分?jǐn)?shù)78.0%、80.0%、81.8%和89.0%)分別成型, 研究發(fā)現(xiàn)固含量為質(zhì)量分?jǐn)?shù)81.8%的漿料制得的樣品性能最優(yōu), 其介電常數(shù)為765, 介電損耗為0.020, 在70 ℃、電場(chǎng)30～40 kV/cm條件下對(duì)樣品極化15 min, 測(cè)得壓電常數(shù)33為300 pC/N。經(jīng)過(guò)阻抗分析測(cè)試發(fā)現(xiàn), 中心頻率為2.24 MHz時(shí), 由固含量為質(zhì)量分?jǐn)?shù)81.8%的漿料制得的陣列具有–6 dB的35%帶寬, 這和傳統(tǒng)的PZT陶瓷傳感器(～31%帶寬)類似。Tiller等[20]則報(bào)道了光固化技術(shù)制備壓電麥克風(fēng), 其區(qū)別于前人的亮點(diǎn)在于運(yùn)用商業(yè)化的3D打印機(jī)完成包括導(dǎo)電層、壓電材料和高分子的復(fù)合器件制造。其中, 在-面的精度為27 μm,軸方向通過(guò)調(diào)整曝光參數(shù)也可以將層厚精度控制在1 μm。雖然該工作制備的器件性能(33約為2～3 pC/N)僅與濺射得到的氮化鋁膜相當(dāng), 并且該工作中多種材料協(xié)同打印依靠人工停止、更換原材料和機(jī)器再啟動(dòng)過(guò)程亦需要改進(jìn), 但不可否認(rèn)的是該工作具有革命性的意義, 即作者以麥克風(fēng)為例, 從原料制備、3D建模、運(yùn)用商業(yè)化的增材制造設(shè)備制備不同幾何形狀的試樣并對(duì)其進(jìn)行封裝、測(cè)試和分析, 完成了原材料–成型–器件的全流程工作, 為今后增材制造壓電器件指明了研究方向。

盡管光固化成型技術(shù)制備的樣品表面光潔度高且打印精度高, 但其需要的原材料用量大、成本高, 對(duì)于尺寸相對(duì)較小的壓電陶瓷及器件而言, 還需對(duì)增材制造設(shè)備進(jìn)行針對(duì)性的設(shè)計(jì), 以制備精度高且尺寸小的壓電陶瓷和器件。

2 直寫(xiě)式打印

作為一種較早發(fā)展起來(lái)的增材制造技術(shù), 直寫(xiě)式打印(Direct ink writing, DIW)最先由美國(guó)桑迪亞國(guó)家實(shí)驗(yàn)室于1997年提出[46], 并先后運(yùn)用于陶瓷、生物玻璃、細(xì)胞和生物組織等材料[47-50]。在陶瓷增材制造領(lǐng)域, 直寫(xiě)式打印技術(shù)常見(jiàn)的原材料為剪切變稀的黏彈性漿料。經(jīng)過(guò)氣動(dòng)或電動(dòng)壓力作用, 漿料通過(guò)微小內(nèi)徑的針頭擠出后, 以層疊的方式構(gòu)建三維模型。在已報(bào)道的文獻(xiàn)中, 常用的針頭內(nèi)徑范圍為1～1000 μm[47-54]。與其他增材制造技術(shù)相比, 該技術(shù)可實(shí)現(xiàn)多材料打印, 并且理論上對(duì)材料的種類和數(shù)量沒(méi)有限制[22]。

直寫(xiě)式打印最初的應(yīng)用與壓電陶瓷相關(guān)。Tuttle和Smay等[55-56]首先將直寫(xiě)式打印應(yīng)用于含鉛壓電陶瓷。他們不僅詳細(xì)闡述了制備過(guò)程, 而且運(yùn)用理論分析不同連接方式(3-3、3-2、3-1)的樣品單元對(duì)壓電性能的貢獻(xiàn)。其中, 直寫(xiě)式打印塊體狀PZT的壓電常數(shù)33和31分別為604和–269 pC/N, 機(jī)電耦合系數(shù)31為0.670, 這與冷等靜壓制備的對(duì)照組樣品性能相近(d33～573 pC/N,31～–255 pC/N,31～0.645)。之后, 他們使用不同尺寸針頭將PZT打印制成線性和環(huán)形, 測(cè)得的介電常數(shù)(1 kHz)分別為831和1081, 壓電常數(shù)33分別為388和496 pC/N[57]。直寫(xiě)式打印PZT壓電陶瓷的樣品宏、微觀形貌如圖4所示, 這些樣品用傳統(tǒng)方法難以制備。

此后, 研究人員探究了直寫(xiě)式打印無(wú)鉛壓電陶瓷。Li等[58]運(yùn)用文獻(xiàn)[43]的材料成分, 即使用Li、Sb和Ta對(duì)KNN粉末進(jìn)行摻雜, 經(jīng)過(guò)兩步法煅燒的技術(shù)路線制備原料粉末。該粉末在聚甲基丙烯酸甲酯(Polymethyl methacrylate, PMMA)和季戊四醇三丙烯酸酯中分散制備固含量為質(zhì)量分?jǐn)?shù) 56%的漿料,進(jìn)行直寫(xiě)式打印獲得3-3連接方式的試樣。經(jīng)1100 ℃燒結(jié), 樣品介電常數(shù)為1775。在2.5 kV/mm電場(chǎng)下對(duì)樣品在100 ℃硅油中極化20 min后, 壓電常數(shù)33為280 pC/N, 剩余極化強(qiáng)度(r)為18.8 μC/cm2,矯頑場(chǎng)(C)為8.5 kV/cm。Gao等[59]將KNN納米線分散在聚二甲基硅氧烷和固化劑(質(zhì)量比10:1)組成的混合物中, 制備固含量為質(zhì)量分?jǐn)?shù) 40%的漿料, 進(jìn)而制備壓電納米驅(qū)動(dòng)器。該漿料打印在事先鍍有Au/Cr電極的聚對(duì)苯二甲酸乙二酯(Polyethylene terephthalate, PET, 150 μm)膜上, 在固化的壓電陶瓷層表面貼上一層鍍有Au/Cr的聚酰胺膜(50 μm), 兩高分子膜之間的陶瓷層厚分別為一層、三層和五層, 分別在0.4、1.2和2.0 kV電壓下進(jìn)行極化。對(duì)含有五層陶瓷的復(fù)合器件連接在電路中進(jìn)行穿戴實(shí)驗(yàn)和彎曲循環(huán)測(cè)試, 結(jié)果表明該器件收集到的能量可以點(diǎn)亮12個(gè)串聯(lián)的LED, 如圖4(f)所示。

圖4 直寫(xiě)式打印壓電陶瓷材料的宏觀、微觀形貌及應(yīng)用

(a-c) PZT in 3-3, 3-2 and 3-1 connectivity (upper and lower pictures show the surface and cross-section of the sample, respectively)[56]; (d) Linear and annular samples with a size bar of 5 mm; (e) Cross-section of LA-2 in (d)[57]; (f) Captured image of 12 LEDs driven by the capacitor charged by KNN/PDMS[59]; (g) Alizarin red staining of BST/40%-TCP composite, indicating the maximum mineral depo-sition with a good biomineralization activity[65]

另一個(gè)重要的無(wú)鉛壓電體系BT也受到研究人員的廣泛關(guān)注。Kim等[60]將BT粉末分散在聚偏氟乙烯(Polyvinylidene fluoride, PVDF)和,-二甲基甲酰胺的混合物中制備漿料。在1 kHz條件下, 經(jīng)1400 ℃燒結(jié)樣品的介電常數(shù)為4730。在0.66 kV/mm電場(chǎng)下對(duì)樣品在80 ℃硅油中極化15 h后, 測(cè)得壓電常數(shù)33為200 pC/N。Lorenz等[61]將中位徑為1.2 μm的BT粉末分散在水中制備固含量為體積分?jǐn)?shù)50%和52%的漿料, 生坯干燥后借助冷等靜壓提高樣品的致密度。經(jīng)過(guò)1350 ℃燒結(jié)3 h后, 在1 kHz條件下測(cè)得樣品的居里點(diǎn)為130 ℃。在2 kV/mm電場(chǎng)下對(duì)樣品在硅油中極化30 min后, 測(cè)得樣品的常溫壓電常數(shù)33分別為165和200 pC/N, 由此可見(jiàn), 漿料固含量和生坯致密度的差異會(huì)影響樣品的最終致密度, 直接體現(xiàn)為壓電常數(shù)的差距。

近年來(lái), BT經(jīng)Ca和Zr共摻雜的材料體系Ba0.85Ca0.15Zr0.1Ti0.9O3(BCZT)因較高的壓電常數(shù)(33～620 pC/N)得到了廣泛關(guān)注[62]。研究人員運(yùn)用直寫(xiě)式打印制備了3-3和1-3連接方式的BCZT[63-64], 通過(guò)調(diào)整粉末粒度分布和分散劑添加量, 提高懸濁液的穩(wěn)定性, 并調(diào)整黏結(jié)劑和絮凝劑的添加量, 得到適合150～410 μm針頭擠出的漿料。經(jīng)1500 ℃燒結(jié)的3-3試樣在1 kHz條件下介電常數(shù)為1046, 常溫介電損耗為0.021, 壓電常數(shù)33為(100±4) pC/N。同時(shí), 研究人員對(duì)比噴墨打印過(guò)程中的按需送料(Drop-on-demand, DOD)原理, 首次提出按需送絲(Filament-on-demand, FOD)的打印模式, 實(shí)現(xiàn)陣列狀1-3試樣的成功制備。

類似地, Sr摻雜BT的體系(Ba,Sr)TiO3(BST)和-磷酸三鈣(-TCP)的復(fù)合多孔支架也由直寫(xiě)式打印法成功制備[65], 以期用于下一代骨組織工程中。BST/()-TCP(=0, 10%, 20%, 30%, 40%, 50%, 均為質(zhì)量分?jǐn)?shù))粉末與PVC溶液混合制備成漿料, 通過(guò)直寫(xiě)式技術(shù)打印為多孔試樣, 其中-TCP含量為40%的組分具有最高的密度和力學(xué)性能指標(biāo), 隨著-TCP添加量提高, 樣品介電性能下降。同時(shí), 該成分的多孔試樣在模擬體液中浸泡28 d后顯示良好的生物活性和相容性, 如圖4(g)所示, 對(duì)樣品表面磷灰石礦化程度分析可知, 隨著-TCP含量增大, 樣品表面的羥基磷灰石含量隨之增大。由此可見(jiàn), BST/40%-TCP試樣兼具良好的生物相容性和力學(xué)性能, 適合成骨細(xì)胞生長(zhǎng)。運(yùn)用增材技術(shù)制造無(wú)鉛壓電陶瓷和生物材料構(gòu)成的復(fù)合材料, 為今后新型超聲輔助成骨細(xì)胞生長(zhǎng)的研究提供了新的思路。

與光固化技術(shù)相比, 雖然直寫(xiě)式打印的樣品表面粗糙度較高且打印過(guò)程會(huì)出現(xiàn)堵頭現(xiàn)象導(dǎo)致打印中斷, 但是其多材料同時(shí)制備的優(yōu)勢(shì)更適合壓電器件的制備。故直寫(xiě)式打印也將成為今后多材料增材制造的重要發(fā)展方向。

3 噴墨打印

噴墨打印是現(xiàn)代印刷中運(yùn)用最廣的技術(shù)。1951年, 第一個(gè)成功使用噴射墨水的產(chǎn)品由Elmquist在瑞典發(fā)明, 隨后, 研究人員分別于1967年和1973年發(fā)明了噴墨打印機(jī)和兩種電信號(hào)控制的噴墨技術(shù)[24]。噴墨打印機(jī)主要分為連續(xù)噴射(Continuous-jet)和按需噴射(Drop-on-demand, DOD)兩種模式, 為了形成氣壓脈沖實(shí)現(xiàn)液滴的按需噴射, 在DOD模式下, 噴頭又可以分為加熱噴射和壓電噴射兩種機(jī)制[66]。噴墨打印陶瓷的報(bào)道始于20世紀(jì)90年代, 主要以ZrO2、TiO2等陶瓷為主[67-70]。

噴墨打印壓電陶瓷的連接方式主要為2-2和1-3。Bhatti等[71]通過(guò)混合乙醇、異丙醇、表面活性劑、黏結(jié)劑作為分散介質(zhì)制備PZT漿料, 噴墨打印1-3連接方式的PZT柱狀陣列, 闡述了漿料的配制方法和與之匹配的打印參數(shù), 并嘗試增加打印層數(shù)以提高陣列單元的高徑比(如圖5所示)。之后, 法國(guó)研究人員深入討論了1-3連接方式的PZT噴墨打印工藝[72-74], 對(duì)漿料提出三點(diǎn)要求: 1)減少沉降; 2)控制漿料干燥過(guò)程, 降低液滴噴射頻率同時(shí)防止堵孔; 3)調(diào)整流體性能, 包括粘度和表面張力。在后續(xù)的工作中, 他們還結(jié)合打印工藝(液滴打印速度、液滴體積、噴嘴尺寸等), 利用激光干涉儀對(duì)單個(gè)液滴成型的柱狀單元進(jìn)行斷層攝影分析, 尋找適合的漿料粘度范圍以及與之匹配的打印參數(shù)。

近年來(lái), 斯洛文尼亞的研究人員摒棄有機(jī)溶劑而使用水作為漿料的分散介質(zhì), 日本的研究人員則直接使用陶瓷前驅(qū)體作為原料進(jìn)行噴墨打印。研究人員[75-77]對(duì)自制原料粉末和漿料進(jìn)行分析, 從粉末粒徑分布、紅外分析和熱分析結(jié)果入手調(diào)整粉末研磨時(shí)間, 測(cè)試墨水的Zeta電位、粘度, 優(yōu)化墨水成分及其穩(wěn)定性。噴墨打印的膜經(jīng)850 ℃燒結(jié)2 h后, 膜厚為15 μm, 1 kHz頻率下測(cè)得的介電常數(shù)為190, 在4 kV/mm電場(chǎng)、120 ℃硅油中對(duì)樣品極化40 min后測(cè)得的壓電常數(shù)33= 3.5 C/m2, 機(jī)電耦合因數(shù)t= 0.46。Wagata等[78]使用BT前驅(qū)體溶液進(jìn)行噴墨打印, 從根本上避免堵孔的發(fā)生。陶瓷前驅(qū)體通過(guò)60 μm直徑的噴嘴直接沉積于360 ℃的熱玻璃上形成圓點(diǎn)。如果玻璃溫度低于360 ℃, 液滴沉積后發(fā)生分散, 圓點(diǎn)的直徑偏差大。此外, 研究人員還通過(guò)控制液滴濃度和體積制備不同直徑的點(diǎn)陣。陶瓷前驅(qū)體隨著玻璃溫度提高, X射線衍射譜圖逐漸由非晶相變?yōu)榫? 到650 ℃成為完全的BT衍射峰。

圖5 噴墨打印柱狀陣列高度差異[71]

(a) Sample printed in 1000 layers; (b) Sample printed in 4000 layers

噴墨打印與直寫(xiě)式打印都是采用液體漿料的直接打印, 兩者的最明顯差異在于漿料粘度: 噴墨打印漿料的粘度一般小于<20 mPa·s, 而直寫(xiě)式打印的漿料粘度一般大于1000 Pa·s(剪切率為0.1 s–1)[25,64,79-83]。噴墨打印雖起步早, 但發(fā)展較慢, 大多數(shù)工作只停留在陶瓷成型層面, 性能報(bào)道較少。近年來(lái), 直寫(xiě)式打印從材料和成型角度的發(fā)展較快, 相關(guān)的功能性能報(bào)道較多。為避免噴嘴堵孔并提高成型精度, 陶瓷前驅(qū)體原料將成為直寫(xiě)式打印和噴墨打印的研究方向。

4 熔融沉積成型

熔融沉積成型是目前商業(yè)化程度最高的增材制造技術(shù), 目前市面上常見(jiàn)的原材料以丙烯腈–丁二烯–苯乙烯共聚物(Acrylonitrile butadiene styrene, ABS)、聚乳酸(Polylactic acid, PLA)和尼龍等高分子聚合物絲材為主, 其他材料亦可通過(guò)小批量訂制獲得。

美國(guó)羅格斯大學(xué)的Safari團(tuán)隊(duì)[27, 82-89]最早將該技術(shù)運(yùn)用于含鉛壓電陶瓷成型領(lǐng)域。他們通過(guò)調(diào)整復(fù)合絲材的材料組成尋找適于打印的成分配比, 結(jié)果表明, PZT絲材的固含量為體積分?jǐn)?shù)55%, 通過(guò)逐層沉積可以直接制備線形試樣(Linear)和輻射狀(Radial)的壓電致動(dòng)器。FDM的生坯含有大量有機(jī)物, 因此如何順利脫除有機(jī)物、保證試樣高致密度是該技術(shù)在后處理過(guò)程中的難點(diǎn)[84]。同時(shí), 研究人員還將該P(yáng)ZT絲材打印成2-2連接方式的環(huán)形試樣和3-3連接方式的多孔試樣, 并借助FDM打印1-3連接方式的模具, 運(yùn)用粉漿澆筑技術(shù)制備1-3連接方式的PZT試樣, 如圖6所示。經(jīng)1285 ℃燒結(jié), 3-3試樣和2-2試樣的介電常數(shù)分別為700和627[85]。經(jīng)電暈極化后, 3-3、1-3、2-2試樣的壓電常數(shù)33分別為(290±10)、(280±10)[85]和(397±16) pC/N[86]。

在無(wú)鉛體系方面, 現(xiàn)階段報(bào)道多以BT體系為主。Castles等[28]通過(guò)制備不同固含量的BT/ABS復(fù)合絲材(固含量為質(zhì)量分?jǐn)?shù)0～70%)打印不同連接方式的BT, 并分析制備過(guò)程中產(chǎn)生缺陷的原因。所有試樣均未經(jīng)燒結(jié), 介電常數(shù)低(<10), 介電損耗大(>0.004)。Kim等[90]將BT與PVDF進(jìn)行復(fù)合, 制備絲材, 再用FDM制備厚度為0.33 mm的厚膜, 用直接混合BT/PVDF成為漿料通過(guò)流延成型制備的試樣作為參照組試樣。兩種方法制備的厚膜均在90 ℃硅油中極化2 h, 極化電場(chǎng)為35 kV/mm。其中, FDM試樣的壓電常數(shù)31為2.1×10–2pC/N, 而流延成型試樣的31僅為9.0×10–3pC/N。本文中部分參考文獻(xiàn)報(bào)道的增材制造壓電陶瓷的功能性能總結(jié)于表2。

圖6 熔融沉積成型的部分樣品的宏觀、微觀形貌

(a) 3-3 porous ladder sample[85]; (b) Wax mould[85]; (c) 1-3 pillar arrays made by lost mould process (mould in (b))[85]; (d) 2-2 linear sample[86]; (e) Left showing 2-2 annular ring and right showing 3-3 ladder structures[85]

雖然FDM是目前最容易獲得的增材制造設(shè)備, 但是市面上的壓電陶瓷絲材不多見(jiàn)。由于復(fù)合絲材含有大量高分子材料, 如何保證打印后樣品的功能性能接近壓電陶瓷的本征性能是目前亟需解決的問(wèn)題。同時(shí), 由于熔融沉積成型的大部分設(shè)備噴嘴精度不高, 導(dǎo)致打印試樣的幾何精度不高, 這也是該技術(shù)今后亟待攻克的方向。

5 總結(jié)與展望

本文探討了目前壓電陶瓷的增材制造技術(shù), 從各種技術(shù)的發(fā)展歷史、已報(bào)道的材料體系入手, 對(duì)增材制造壓電陶瓷原材料的制造工藝、樣品的性能表征及其應(yīng)用進(jìn)行闡述、對(duì)比。從材料體系而言, 增材制造壓電陶瓷從含鉛體系逐步發(fā)展到以BT和KNN體系為主、其他摻雜體系為輔的無(wú)鉛體系。從連接方式而言, 樣品以3-3、1-3、2-2為主, 引入超材料結(jié)構(gòu)可以帶來(lái)新的思路。光固化和直寫(xiě)式打印比噴墨打印和熔融沉積成型的學(xué)術(shù)型研究更多, 這從側(cè)面反映了增材制造的方向——即高精度和多材料制造。從功能性能而言, 部分樣品的介電、壓電性能已達(dá)到與本征性能相近的水平, 但是增材制造樣品的綜合性能仍有提升空間。雖然現(xiàn)階段黏結(jié)劑噴射技術(shù)應(yīng)用于壓電陶瓷領(lǐng)域的文獻(xiàn)較少, 本文未予評(píng)述, 但不可否認(rèn)的是, 在工業(yè)界通用、惠普、武漢易制等國(guó)內(nèi)外企業(yè)都已推出針對(duì)黏結(jié)劑噴射技術(shù)的3D打印陶瓷解決方案, 發(fā)展速度迅猛。

盡管增材制造壓電陶瓷的成型問(wèn)題已基本解決, 下一步該領(lǐng)域的研究仍需要從細(xì)節(jié)入手, 在原料優(yōu)化、幾何外形的合理設(shè)計(jì)、樣品后處理等方面努力, 以改善增材制造試樣的功能性能, 為增材制造壓電器件打好基礎(chǔ)。原材料的制備過(guò)程需要提高納米粉體的分散性和漿料的穩(wěn)定性, 使用陶瓷前驅(qū)體作為原料實(shí)現(xiàn)更高精度樣品的制備, 同時(shí)多材料打印也有利于推動(dòng)有機(jī)–無(wú)機(jī)壓電復(fù)合材料的發(fā)展。幾何外形設(shè)計(jì)要在現(xiàn)有3D設(shè)計(jì)切片軟件的基礎(chǔ)上, 將增材制造工藝與軟件編程相結(jié)合, 實(shí)現(xiàn)路徑的最優(yōu)化設(shè)計(jì)。在樣品后處理方面, 從固化工藝或排膠、燒結(jié)工藝入手, 避免不合理工藝帶來(lái)的缺陷, 保證樣品的致密度。性能測(cè)試前的極化工藝包括極化方法、極化電壓、極化時(shí)間等需要大量實(shí)驗(yàn)驗(yàn)證, 以發(fā)揮試樣的綜合性能。另外, 由于壓電陶瓷在外場(chǎng)作用下產(chǎn)生微小的尺寸變化, 故在電場(chǎng)作用下的4D打印壓電陶瓷也是值得探索的方向。

表2 增材制造壓電陶瓷功能性能

[1] XU S, HANSEN B J, WANG Z L. Piezoelectric-nanowire-enabled power source for driving wireless microelectronics., 2010, 1: 93.

[2] VAN DEN ENDE D A, VAN DE WIEL H J, GROEN W A,Direct strain energy harvesting in automobile tires using piezoelectric PZT-polymer composites., 2012, 21: 015011.

[3] XU X H, LI H. Photoacoustic imaging in biomedicine., 2008, 37(2): 111–119.

[4] CARULLO A, PARVIS M. An ultrasonic sensor for distance measurement in automotive applications., 2001, 1(2): 143.

[5] ROUNDY S, WRIGHT P K. A piezoelectric vibration based generator for wireless electronics., 2004, 13(5): 1131.

[6] SWARTZ S L. Topics in electronic ceramics., 1990, 25(5): 935–987.

[7] MATTOX J M. Additive manufacturing and its implications for military ethics., 2013, 12(3): 225–234.

[8] IBN-MOHAMMED T, KOH S C L, REANEY I M,Integrated hybrid life cycle assessment and supply chain environ-mental profile evaluations of lead-based (lead zirconate titanate)lead-free (potassium sodium niobate) piezoelectric ceramics., 2016, 9(11): 3495–3520.

[9] BELL A J, DEUBZER O. Lead-free piezoelectrics-the environ-mental and regulatory issues., 2018, 43(8): 581–587.

[10] NEWNHAM R E, SKINNER D P, CROSS L E. Connectivity and piezoelectric-pyroelectric composites., 1978, 13(5): 525–536.

[11] JANTUNEN H, HU T, Uusim?ki A,Tape casting of ferroelectric, dielectric, piezoelectric and ferromagnetic materials., 2004, 24(6): 1077–1081.

[12] PARK G T, CHOI J J, PARK C S,Piezoelectric and ferroelectric properties of 1-μm-thick lead zirconate titanate film fabricated by a double-spin-coating process., 2004, 85(12): 2322–2324.

[13] SAVAKUS H P, KLICKER K A, NEWNHAM R E. PZT-epoxy piezoelectric transducers: a simplified fabrication procedure., 1981, 16(6): 677–680.

[14] GARCíA-GANCEDO L, OLHERO S M, ALVES F J,Application of gel-casting to the fabrication of 1-3 piezoelectric ceramic-polymer composites for high-frequency ultrasound devices., 2012, 22(12): 125001.

[15] LEJEUNE M, CHARTIER T, DOSSOU-YOVO C,Ink-jet printing of ceramic micro-pillar arrays., 2006, 45: 413–420.

[16] ICHIDA Y. Current status of 3D printer use among automotive suppliers: can 3D printed-parts replace cast parts., 2016, 5: 69–82.

[17] Nichols M R. How does the automotive industry benefit from 3D metal printing?, 2019, 74(5): 257–258.

[18] LAMBERT P, CHARTRAIN N, SCHULTZ A,Mask Projection Microstereolithography of Novel Biocompatible Poly-mers. International Solid Freeform Fabrication Symposium, 2014: 974–990.

[19] SONG X, CHEN Z, LEI L,Piezoelectric component fabrication using projection-based stereolithography of barium titanate ceramic suspensions., 2017, 23(1): 44–53.

[20] TILLER B, REID A, ZHU B,Piezoelectric microphonea digital light processing 3D printing process., 2019, 165: 107593.

[21] OVHAL M M, KUMAR N, KANG J W. 3D direct ink writing fabrication of high-performance all-solid-state micro-supercapacitors., 2020, 705(1): 105–111.

[22] TRUBY R L, LEWIS J A. Printing soft matter in three dimensions., 2016, 540(7633): 371–378.

[23] CHU Y, QIAN C, CHAHAL P,Printed diodes: materials processing, fabrication, and applications., 2019, 6(6): 1801653.

[24] HEINZL J, HERTZ C H. Ink-jet printing., 1985, 65: 91–171.

[25] WANG T, DERBY B. Ink-jet printing and sintering of PZT., 2005, 88(8): 2053–2058.

[26] LEE K Y, CHO J W, CHANG N Y,Accuracy of three-dimensional printing for manufacturing replica teeth., 2015, 45(5): 217–225.

[27] SAFARI A, CESARANO J, CLEM P G,Fabrication of Advanced Functional Electroceramic Components by Layered Manufacturing (LM) Methods. Proceedings of the 13th IEEE International Symposium on Applications of Ferroelectrics, 2002. ISAF, Japan, 2002: 1–6.

[28] CASTLES F, ISAKOV D, LUI A,Microwave dielectric characterisation of 3D-printed BaTiO3/ABS polymer composites., 2016, 6: 22714.

[29] PARUPELLI S, DESAI S. A comprehensive review of additive manufacturing (3D printing): processes, applications and future potential., 2019, 16(8): 244–272.

[30] BáRTOLO P J. Stereolithography: Materials, Processes and Applications. Boston: Springer Science & Business Media, 2011: 42.

[31] SWAINSON W K. Method, Medium and Apparatus for Producing Three-dimensional Figure Product. US Patent, 4041476. 1977-08-09.

[32] HULL C W. Apparatus for Production of Three-dimensional Objects by Stereolithography. US Patent, 45753301. 1986-03-11.

[33] HULL C W, SPENCE S T, ALBERT D J,Methods and Apparatus for Production of Three-dimensional Objects by Stereolithography. US Patent, 5059359. 1991-10-22.

[34] LI S, DUAN W, ZHAO T,The fabrication of SiBCN ceramic components from preceramic polymers by digital light processing (DLP) 3D printing technology., 2018, 38(14): 4597–4603.

[35] He C, Liu X, Ma C,Digital light processing fabrication of mullite component derived from preceramic precursor using photosensitive hydroxysiloxane as the matrix and alumina nanoparticles as the filler., 2021, 41(11): 5570–5577

[36] DUFAUD O, MARCHAL P, Corbel S. Rheological properties of PZT suspensions for stereolithography., 2002, 22(13): 2081–2092.

[37] DUFAUD O, CORBEL S. Oxygen diffusion in ceramic suspensions for stereolithography., 2003, 92(1/2/3): 55–62.

[38] DUFAUD O, CORBEL S. Application of stereolithography to chemical engineering: ‘from macro to micro’., 2005, 83(2): 133–138.

[39] KIM K, ZHU W, QU X,3D optical printing of piezoelectric nanoparticle-polymer composite materials., 2014, 8(10): 9799–9806.

[40] CHEN Z, SONG X, LEI L,3D printing of piezoelectric element for energy focusing and ultrasonic sensing., 2016, 27: 78–86.

[41] VIJATOVI? M M, BOBI? J D, STOJANOVI? B D. History and challenges of barium titanate: Part II., 2008, 40(3): 235–244.

[42] CHEN W, WANG F, YAN K,Micro-stereolithography of KNN-based lead-free piezoceramics., 2019, 45(4): 4880–4885.

[43] SAITO Y, TAKAO H, TANI T,Lead-free piezoceramics., 2004, 432(7013): 84–87.

[44] CUI H, HENSLEIGH R, YAO D,Three-dimensional printing of piezoelectric materials with designed anisotropy and directional response., 2019, 18(3): 234–241.

[45] CHEN Y, BAO X, WONG C M,PZT ceramics fabricated based on stereolithography for an ultrasound transducer array application., 2018, 44(18): 22725–22730.

[46] CESARANO III J, CALVERT P D. Freeforming Objects with Low-binder Slurry. US Patent, 6027326. 2000-02-22.

[47] MORISSETTE S L, LEWIS J A, CESARANO J,Solid freeform fabrication of aqueous alumina-poly(vinyl alcohol) gelcasting suspensions., 2000, 83(10): 2409–2416.

[48] DUOSS E B, TWARDOWSKI M, LEWIS J A. Sol-Gel inks for direct-write assembly of functional oxides., 2007, 19(21): 3485–3489.

[49] MARQUES C F, PERERA F H, MAROTE A,Biphasic calcium phosphate scaffolds fabricated by direct write assembly: mechanical, anti-microbial and osteoblastic properties., 2017, 37(1): 359–368.

[50] KOLESKY D B, TRUBY R L, GLADMAN A S,3D bioprinting of vascularized, heterogeneous cell-laden tissue constructs., 2014, 26(19): 3124–3130.

[51] KOLESKY D B, HOMAN K A, SKYLAR-SCOTT M A,Three-dimensional bioprinting of thick vascularized tissues., 2016, 113(12): 3179–3184.

[52] SMAY J E, CESARANO J, LEWIS J A. Colloidal inks for directed assembly of 3-D periodic structures., 2002, 18(14): 5429–5437.

[53] WANG R, ZHU P, YANG W,Direct-writing of 3D periodic TiO2bio-ceramic scaffolds with a Sol-Gel ink forcell growth., 2018, 144: 304–309.

[54] CHEN T, SUN A, CHU C,Rheological behavior of titania ink and mechanical properties of titania ceramic structures by 3D direct ink writing using high solid loading titania ceramic ink., 2019, 783: 321–328.

[55] TUTTLE B A, SMAY J E, CESARANO J,Robocast Pb(Zr0.95Ti0.05)O3ceramic monoliths and composites., 2001, 84(4): 872–874.

[56] SMAY J E, CESARANO III J, TUTTLE B A,Piezoelectric properties of 3-X periodic Pb(ZrTi1–x)O3-polymer composites., 2002, 92(10): 6119–6127.

[57] SMAY J E, CESARANO III J, TUTTLE B A,Directed colloidal assembly of linear and annular lead zirconate titanate arrays., 2004, 87(2): 293–295.

[58] LI Y, LI L, LI B. Direct ink writing of three-dimensional (K, Na)NbO3- based piezoelectric ceramics., 2015, 8(4): 1729–1737.

[59] GAO M, LI L, LI W,Direct writing of patterned, lead-free nanowire aligned flexible piezoelectric device., 2016, 3(8): 1600120.

[60] KIM H, RENTERIA-MARQUEZ A, ISLAM M D,Fabrication of bulk piezoelectric and dielectric BaTiO3ceramics using paste extrusion 3D printing technique., 2019, 102(6): 3685–3694.

[61] LORENZ M, MARTIN A, WEBBER K G,Electro-me-chanical properties of Robocasted barium titanate ceramics., 2020, 22(9): 2000325.

[62] LIU W, REN X. Large piezoelectric effect in Pb-free ceramics., 2009, 103(25): 257602.

[63] NAN B, OLHERO S, PINHO R,Direct ink writing of macroporous lead-free piezoelectric Ba0.85Ca0.15Zr0.1Ti0.9O3., 2019, 102(6): 3191–3203.

[64] NAN B, GALINDO-ROSALES F J, FERREIRA J M F. 3D printing vertically: direct ink writing free-standing pillar arrays., 2020, 35: 16–24.

[65] TARIVERDIAN T, BEHNAMGHADER A, MILAN P B,3D-printed barium strontium titanate-based piezoelectric scaffolds for bone tissue engineering., 2019, 45(11): 14029–14038.

[66] DERBY B. Inkjet printing of functional and structural materials: fluid property requirements, feature stability, and resolution., 2010, 40: 395–414.

[67] BLAZDELL P F, EVANS J R G, EDIRISINGHE M J,The computer aided manufacture of ceramics using multilayer jet printing., 1995, 14(22): 1562–1565.

[68] XIANG Q F, EVANS J R G, EDIRISINGHE M J,Solid freeforming of ceramics using a drop-on-demand jet printer., 1997, 211(3): 211–214.

[69] ZHAO X, EVANS J R G, EDIRISINGHE M J,Direct ink-jet printing of vertical walls., 2002, 85(8): 2113–2115.

[70] TENG W D, EDIRISINGHE M J, EVANS J R G. Optimization of dispersion and viscosity of a ceramic jet printing ink., 1997, 80(2): 486–494.

[71] BHATTI A R, MOTT M, EVANS J R G,PZT pillars for 1-3 composites prepared by ink-jet printing., 2001, 20(13): 1245–1248.

[72] NOGUERA R, DOSSOU-YOVO C, LEJEUNE M,Fabrication of 3D fine scale PZT components by ink-jet prototyping process., 2005, 128: 87–93.

[73] NOGUERA R, LEJEUNE M, CHARTIER T. 3D fine scale ceramic components formed by ink-jet prototyping process., 2005, 25(12): 2055–2059.

[74] LEJEUNE M, CHARTIER T, DOSSOU-YOVO C,Ink-jet printing of ceramic micro-pillar arrays., 2009, 29(5): 905–911.

[75] NOSHCHENKO O, KUSCER D, MOCIOIU O C,Effect of milling time and pH on the dispersibility of lead zirconate titanate in aqueous media for inkjet printing., 2014, 34(2): 297–305.

[76] BAKARI? T, MALI? B, KUSCER D. Lead-zirconate-titanate- based thick-film structures prepared by piezoelectric inkjet printing of aqueous suspensions., 2016, 36(16): 4031–4037.

[77] KUSCER D, DRNOV?EK S, LEVASSORT F. Inkjet-printing- derived lead-zirconate-titanate-based thick films for printed ele-ctronics., 2020, 198: 109324.

[78] WAGATA H, GALLAGE R, YOSHIMURA M,Patterning of BaTiO3by inkjet deposition using a precursor solution., 2009, 161(1/2/3): 146–150.

[79] Seerden K A, Reis N, Evans J R,. Ink-jet printing of wax-based alumina suspensions., 2001, 84(11): 2514–2520.

[80] VADILLO D C, TULADHAR T R, MULJI A C,The rheological characterization of linear viscoelasticity for ink jet fluids using piezo axial vibrator and torsion resonator rheometers., 2010, 54(4): 781–795.

[81] LEWIS J A. Direct ink writing of 3D functional materials., 2006, 16(17): 2193–2204.

[82] SCHLORDT T, SCHWANKE S, KEPPNER F,Robocasting of alumina hollow filament lattice structures., 2013, 33: 3243–3248.

[83] MUTH J T, VOGT D M, TRUBY R L,Embedded 3D printing of strain sensors within highly stretchable elastomers., 2014, 26(36): 6307–6312.

[84] MCNULTY T F, MOHAMMADI F, BANDYOPADHYAY A,Development of a binder formulation for fused deposition of ceramics., 1998, 4(4): 144–150.

[85] BANDYOPADHYAY A, PANDA R K, MCNULTY T F,Piezoelectric ceramics and compositesrapid prototyping techniques., 1998, 4(1): 37–49.

[86] LOUS G M, CORNEJO I A, MCNULTY T F,Fabrication of piezoelectric ceramic/polymer composite transducers using fused deposition of ceramics., 2000, 83(1): 124-128.

[87] BRENNAN R E, TURCU S, HALL A,Fabrication of electroceramic components by layered manufacturing (LM)., 2003, 293(1): 3–17.

[88] SAFARI A, ALLAHVERDI M, AKDOGAN E K. Solid freeform fabrication of piezoelectric sensors and actuators., 2006, 41: 177–198.

[89] SAFARI A, AKDOGAN E K. Rapid prototyping of novel piezoelectric composites., 2006, 331(1): 153–179.

[90] KIM H, FERNANDO T, LI M,Fabrication and characterization of 3D printed BaTiO3/PVDF nanocomposites., 2018, 52(2): 197–206.

Recent Progress on Additive Manufacturing of Piezoelectric Ceramics

NAN Bo1,2, ZANG Jiadong3, LU Wenlong3, YANG Tingwang3, ZHANG Shengwei3, ZHANG Haibo1,2

(1. State Key Laboratory of Materials Processing and Die & Mould Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China; 2. Guangdong HUST Industrial Technology Research Institute, Dongguan 523808, China; 3. Shenzhen Geekvape Technology Co., Ltd., Shenzhen 518100, China)

Piezoelectric ceramic is a type of functional ceramic, which is able to convert the mechanical signal and the electronic signal mutually. Composed of piezoelectric ceramics and organic phase, piezoelectric composites have different kinds of connectivities, which not only determine the diverse applications of piezoelectric devices, but also promote the development of various shaping techniques in manufacturing piezoelectric materials and devices. In comparison with the traditional shaping methods, the most distinguishable advantage of additive manufacturing lies in its ability of quickly shaping a small batch of samples into geometrically complex designs without a mould, which makes it a highly suitable technique for investigating piezoelectric ceramics and its derivative devices in different kinds of connectivities. Meanwhile, the final additively manufactured samples require only tiny post-processing, have a high rate of utilization of the raw material and do not need cutting fluid during manufacturing. Due to the above-mentioned advantages, it attracts the widespread concerns from both academic and industrial communities. When focusing in the field of additive manufacturing ceramics, the data of scientific reports in additive of manufacturing functional ceramics and devices prove that it is still in a growing period. In the perspective of different additive manufacturing techniques, this article discusses and compares additive manufacturing of both lead-free and lead-based piezoelectric ceramics in the aspects of their historical development of each technique, preparation of the raw materials, geometrical designs, measurement of functional properties, and applications of the printed samples, and forecasts the future development based on the current benefits and drawbacks of each additive manufacturing technique.

additive manufacturing; lead-based piezoceramics; lead-free piezoceramics; functional property; review

1000-324X(2022)06-0585-11

10.15541/jim20210358

TM282

A

2021-06-07;

2021-08-18;

2021-11-01

廣東華中科技大學(xué)工業(yè)技術(shù)研究院廣東省制造裝備數(shù)字化重點(diǎn)實(shí)驗(yàn)室(2020B1212060014); 東莞市引進(jìn)創(chuàng)新科研團(tuán)隊(duì)計(jì)劃(2020607101007)

Guangdong HUST Industrial Technology Research Institute, Guangdong Provincial Key Laboratory of Digital Manu-facturing Equipment (2020B1212060014); Dongguan Innovative Research Team Program (2020607101007)

南博(1989–), 男, 博士. E-mail: bonan@hust.edu.cn

NAN Bo (1989–), male, PhD. E-mail: bonan@hust.edu.cn

張海波, 教授. E-mail: hbzhang@hust.edu.cn

ZHANG Haibo, professor. E-mail: hbzhang@hust.edu.cn