Abstract
摘要:此計畫主要研究方向為金屬陶瓷複合材的功能性質,如機械、介電、鐵電及鐵磁性質的研究。
金屬陶瓷複合材是導體與絕緣體的結合,除了電阻的差異外,因金屬與陶瓷兩者的鍵結不同,其他的性質也有很大的不同,因此將兩者組合將會產生很多與基本性質不同的特性,近來的研究已證實金屬陶瓷複合材擁有許多有趣的特質。
金屬奈米顆粒和塊材相比擁有其他不同的特性,在金屬陶瓷複合材中加入金屬奈米顆粒可以加強其硬度及可靠度,任何元件或產品皆需要好的機械性質可靠度,即使元件是設計使用其光學或是電學性質,奈米顆粒也可能改變金屬陶瓷複合材的功能性,如介電、鐵電及鐵磁等性質。
鈦酸鋇陶瓷除了是良好的介電材料外也是可以自極化的鐵電材料,當施加電場時會產生極化的遲滯現象。鎳為鐵磁材料,當施加電場時會產生磁化的遲滯現象。使用鈦酸鋇加鎳來發展雙相複合材以研發複合功能性材料是一種很好的選擇,因此本研究的重點為鈦酸鋇及鎳複合材的製程發展、微結構及特性的鑑定。
製作鈦酸鋇及鎳複合材是很大的挑戰,金屬鎳必須在低氧分壓的情況下燒結,鎳才不至於氧化。但是高溫低氧分壓的狀況會造成鈦酸鋇內的自由電子增加進而降低電阻,可以利用加入受體的方式來阻止電子濃度的增加,依本團隊之前的研究顯示,當鎳與鈦酸鋇共燒時可以作為鈦酸鋇的受體,在本計劃中將會嘗試發展出最佳製作鈦酸鋇與鎳複合材的製程。
SPS (spark plasma sintering)是新型燒結技術,使用SPS燒結可以製作出擁有金屬奈米顆粒的複合材,本計劃將嘗試製作鈦酸鋇加入奈米氧化鎳的複合材,目前文獻上此奈米複合材尚未有任何報告出現。
本研究將會整合西班牙(CSIC)、大陸(武漢理工大學)及本校的實驗資源及成果,期望能對鈦酸鋇加鎳的複合材有更多的了解並能加強其應用價值。
Abstract: In the present study, the functional properties, such as mechanical, dielectric, ferro-electric and ferro-magnetic, of ceramic-metal composites are the key issues to be investigated.
The ceramic-metal composite is a combination of insulator and conductor. Apart from the difference in electrical resistivity, many properties of ceramic and metal exhibit distinct difference due to their difference in bonding characteristics. Therefore, the combination of ceramic and metal may offer many possible combinations. Recent studies demonstrated that the several interesting properties can be incorporated into the ceramic-metal composites.
Compare to micro-particles, metal nano-particles have many different character. Adding metal nano-particles into ceramic-metal composite will enhance the composite mechanical properties. For example, Ni nanoparticles enhance hardness and reliability of BaTiO3-Ni nano-composite. Most of technological applications containing metal-ceramic composites require strong reliability, even if these are designed for their electrical or optical properties. The nanoparticles may also change the functional properties, such as dielectric, ferro-electric and ferro-magnetic, of ceramic-metal composites.
Barium tiatanate is not only a dielectric materials, it is also a ferroelectric material with spontaneous polarization that can be switched hysteretically by an applied electric field. Nickel is ferromagnetic material that possesses a spontaneous magnetization that can be switched hysteretically by an applied magnetic field. To develop two-phase composite by using BaTiO3 and Ni is an alternative to develop multi-ferroics. In the present study, the processing-microstructure-properties of BaTiO3-Ni composites will be investigated.
The processing of BaTiO3-Ni composite is a very challenging task. Metallic nickel has to be sintered in a low oxygen partial pressure to avoid the oxidation during co-firing of BaTiO3 and Ni. But the firing of BaTiO3 in a low oxygen partial pressure may increase the concentration of free electrons. The increase of electron concentration is detrimental to the insulating resistance of BaTiO3. The key to solve the problem is the solution of acceptors. In fact, we have found out that the Ni is acting as acceptor to BaTiO3 during its cofiring with BaTiO3. The presence of Ni solute can increase the reduction resistance of the BaTiO3. In the present study, we will try to define a process window for the preparation of BaTiO3-Ni insulators.
SPS (spark plasma sintering) technique is a novel process to dense composites. The SPS would be used and allow us to prepare BaTiO3-Ni nanocomposites. The properties of the BaTiO3-Ni nanocomposites have never been reported by any research group.
There are three research groups are working on this project: Prof. Moya Group (Spain), Prof. Zhang Group (P.R.China) and Our Group. The proposed work combines the research resources of three research groups to work on the basic understanding of ceramic-metal composites. Based on the existing data, the BaTiO3-Ni may offer many possible applications.
Keyword(s)
複合材料
陶瓷
金屬
多功能
composite ceramics metals multi-function