本文關鍵詞： 鉻硼化合物 硬質材料 維氏硬度 高溫高壓 多功能材料　出處：《吉林大學》2017年碩士論文　論文類型：學位論文

【摘要】：過渡金屬具有較高的價電子密度,具有極強的抵抗體積壓縮的能力,但是由于抗剪切能力不強,導致硬度值較低,在過渡金屬當中引入方向性極強的硼-硼共價鍵,其所形成的化合物可具有極強的抵抗體積形變能力與較高的抗剪切形變能力,是一種潛在的超硬材料。過渡金屬硼化物以其較高的硬度、強抗氧化性、抗磨損性、化學惰性、導電和導熱等多種優(yōu)良性能已經(jīng)廣泛應用于生產(chǎn)生活中。本論文通過高溫高壓合成系統(tǒng)研究了幾種鉻硼化合物的制備,并且對鉻硼化合物的結構、硬度、磁性、抗氧化性進行了深入的研究,得到了以下結果:通過高溫高壓的方法探索了不同配比的鉻硼化合物的合成條件,在5.0 GPa、15 min、不同的溫度、不同摩爾比的條件下成功合成出了高質量的Cr B、Cr_3B_4和Cr B_2多晶樣品。對Cr B、Cr_3B_4和Cr B_2樣品的X射線衍射結果進行了Rietveld精修。通過對合成塊體多晶樣品的密度、掃描、抗氧化性、硬度、磁性等物性表征,發(fā)現(xiàn)隨著硼濃度的升高,鉻硼化合物中的硼原子亞結構依次經(jīng)歷了以下的變化:Cr B晶體中的“Z”字形鏈→Cr_3B_4晶體中的聚合硼“Z”字形雙鏈→Cr B_2晶體中的類石墨烯狀硼層結構→Cr B4晶體中的三維籠狀結構。硬度測試結果表明隨著硼原子骨架引入鉻金屬骨架當中,鉻硼化合物的硬度值相比鉻金屬得到了極大的提升,達到了硬質材料的標準。隨著硼濃度的提升,鉻硼化物的硬度呈現(xiàn)先升高、后降低、再升高的變化規(guī)律,從而證明過渡金屬輕元素化合物的硬度值除與輕元素濃度有關外,還與輕元素所構成的亞結構有關。磁性測試結果表明隨著硼原子骨架引入鉻金屬骨架當中,由于硼原子亞結構對鉻金屬原子間的擴展,使得Cr B、Cr_3B_4和Cr B_2的磁性發(fā)生了一定的變化。其分別經(jīng)歷了順磁性、超順磁性、反鐵磁性、順磁性的變化。熱重-差熱測試表明Cr B、Cr_3B_4和Cr B_2的抗氧化能力要比金剛石及工業(yè)中廣泛應用的硬質材料碳化鎢等強許多,達到了1000℃以上。利用高壓原位同步輻射的測量方法對Cr_3B_4的晶體結構變化進行了研究。分析了Cr_3B_4晶胞的抗壓縮性、晶格常數(shù)軸向的壓縮情況。我們發(fā)現(xiàn)正交結構的Cr_3B_4晶體結構在壓力達到25 GPa左右時,其晶體結構依然保持穩(wěn)定,并沒有發(fā)生結構相變,說明該結構具有強穩(wěn)定性。正交結構Cr_3B_4晶體結構當中的聚合“Z”字形鏈具有極強的共價性,所以Cr_3B_4在c軸方向具有強抗壓縮能力。通過與常見的硬質(超硬)材料的抗壓縮性對比發(fā)現(xiàn),Cr_3B_4較低的體彈性模量導致其硬度值并沒有達到超硬材料的標準,但是由于其中加入了強共價性的聚合“Z”字形鏈,導致其硬度相對于鉻金屬有較大的提高。
[Abstract]:Transition metals have high valence electron density and strong resistance to volume compression. However, due to the low shear resistance, the hardness of transition metals is lower, so the highly directional boron-boron covalent bond is introduced into the transition metals. The resulting compounds have a strong resistance to volume deformation and high shear deformation resistance, and are potential superhard materials. Transition metal boride is characterized by its high hardness, strong oxidation resistance, wear resistance and chemical inertia. Many excellent properties, such as conductive and thermal conductivity, have been widely used in production and life. In this paper, the preparation of several kinds of chromium-boron compounds has been studied by high-temperature and high-pressure synthesis system, and the structure, hardness, magnetic properties of chromium-boron compounds have been studied. The oxidation resistance was studied in depth. The following results were obtained: the synthesis conditions of different ratios of chromium and boron compounds were explored by high temperature and high pressure method, at 5. 0 GPA for 15 min, at different temperatures, High quality polycrystalline samples of CrBX Cr3B4 and CrB2 have been successfully synthesized under different molar ratios. The X-ray diffraction results of CrBX Cr3B4 and CrBST2 samples have been refined by Rietveld. The density, scanning and oxidation resistance of the synthesized bulk polycrystalline samples have been studied. Hardness, magnetism and other physical properties were characterized. It was found that with the increase of boron concentration, the substructure of boron atoms in chromium-boron compounds underwent the following changes in turn: "Z" zigzag chain in the crystal of "Cr B" 鈫抁igzag double chains of Polyboron "Z" in Cr_3B_4 crystals. 鈫扴tructure of graphene like boron layer in Cr BZ _ 2 crystal. 鈫扵he hardness test results show that with the introduction of the boron atomic skeleton into the chromium metal skeleton, the hardness of the chromium-boron compounds is greatly improved than that of the chromium metal. With the increase of boron concentration, the hardness of chromium boride increases first, then decreases, and then increases. It is proved that the hardness of transition metal light element compounds is related to the concentration of light elements. The magnetic test results show that with the introduction of the boron atomic skeleton into the chromium metal skeleton, the boron atomic substructure extends to the chromium metal atom. The magnetic properties of CrBX and CrB2 have changed to some extent. They have undergone paramagnetism, superparamagnetism and antiferromagnetism, respectively. The change of paramagnetism. Thermogravimetry and differential thermal analysis showed that the oxidation resistance of Cr BX CrS 3B4 and Cr BSP 2 was much stronger than that of diamond and tungsten carbide, a hard material widely used in industry. The crystal structure changes of Cr_3B_4 were studied by means of high voltage in situ synchrotron radiation measurement. The compressibility of Cr_3B_4 cell was analyzed. The axial compression of lattice constants. We find that the structure of Cr_3B_4 crystal with orthogonal structure remains stable and no phase transition occurs when the pressure reaches about 25 GPa. It shows that the structure has strong stability, and the polymerized "Z" zigzag chain in the Cr_3B_4 crystal structure of orthogonal structure has very strong covalent property. So Cr_3B_4 has strong compression resistance in the c-axis direction. By comparing it with the compression resistance of common hard (superhard) materials, it is found that the lower bulk elastic modulus of Cr3B4 results in a hardness value that is not up to the standard of superhard materials. However, due to the addition of a strong covalent "Z" zigzag chain, the hardness of the zigzag chain is higher than that of chromium metal.
【學位授予單位】：吉林大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O52

【相似文獻】

相關期刊論文 前1條

1 張國敏;張招貴;張永茂;陳志偉;;硼化合物研究Ⅶ.BnHn~2-及B_3H_8和C-5H_5FeC_5H_4CH_2N(H)Me_2C1及Fe[C_5H_4CH_2N(H)Me_2C1]_2的反應[J];武漢大學學報(自然科學版);1984年01期

相關會議論文 前4條

1 劉慧;吳延平;盧華;李志芳;沈珍;;新型不對稱氟硼化合物的合成及性質研究[A];中國化學會第29屆學術年會摘要集——第05分會：無機化學[C];2014年

2 李曉艷;李沙瑜;楊國強;;水溶性三芳基硼化合物的合成[A];第十三屆全國光化學學術討論會論文集[C];2013年

3 張曉清;武海順;;羰基硼化合物B_6(CO)_n(n=1-6)的結構與穩(wěn)定性[A];中國化學會第九屆全國量子化學學術會議暨慶祝徐光憲教授從教六十年論文摘要集[C];2005年

4 楊國強;馮嬌;李沙瑜;胡睿;王雙青;;新型溫度熒光探針及其應用[A];第八屆全國光生物學學術會議論文摘要集[C];2013年

相關碩士學位論文 前3條

1 金峰;硼化合物對C_f/LAS復合材料的微觀結構及性能影響[D];哈爾濱工業(yè)大學;2016年

2 張曉梅;新型1,8-萘啶氟硼化合物與鈷卟啉類衍生物的合成及性質研究[D];云南師范大學;2016年

3 朱晶;鉻硼化合物的高溫高壓制備及物性研究[D];吉林大學;2017年

，

本文編號：1529482