钨酸钠与天然土状石墨在高温氩气氛围中的转化过程

doi:10.13209/j.0479-8023.2016.052

摘要/Abstract

摘要：

以 Na₂WO₄为钨源, 天然土状石墨为碳源, 研究二者在高温氩气气氛下的转化过程及规律, 利用 X 射线衍射(XRD)、扫描电子显微镜(SEM)及电子能谱(EDS)对产物进行分析。结果表明, Na₂WO₄与石墨的混合样品在氩气气氛下经高温处理, 可以生成不同的碳钨化合物。首先, 石墨与 Na₂WO₄在接触界面发生还原反应, 将Na₂WO₄还原为α-W₂C和β-W₂C; 然后, 随着石墨增多, 当Na₂WO₄与石墨的质量比小于1:1时, 石墨开始将 α-W₂C 还原为 α-WC, 直至 Na₂WO₄与石墨的质量比为 1:5 时, 石墨可以将 α-W₂C 完全转化为 α-WC。

关键词: 石墨, Na₂WO₄, WC, 高温处理, X射线衍射(XRD), 扫描电子显微镜(SEM), 电子能谱(EDS)

Abstract:

Using sodium tungstate as tungsten source, natural soil shaped graphite as carbon source, an experiment is provided for researching the transformation process and rules of them in argon atmosphere at high temperature. The final products are studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), etc. The result shows that the mixed samples of sodium tungstate and graphite can generate different tungsten carbon compounds in an argon atmosphere with heat treatment. First, reduction reaction occurs between mixed graphite and sodium tungstate dihydrate at the reaction interface, reducing sodium tungstate dihydrate to α-W₂C and β-W₂C. Second, when the mass ratio of Na₂WO₄: C is less than 1:1, reduction of α-W₂C to α-WC occurs, till the mass ratio was 1:5, and α-W₂C can be reduced to α-WC completely.

Key words: graphite, sodium tungstate, tungsten carbide, high-temperature treatment, XRD, SEM, EDS

中图分类号:

P579

魏霖荫, 传秀云, 黄杜斌, 苏双青, 金时运. 钨酸钠与天然土状石墨在高温氩气氛围中的转化过程[J]. 北京大学学报自然科学版, 2017, 53(1): 50-56.

Linyin WEI, Xiuyun CHUAN, Dubin HUANG, Shuangqing SU, Shiyun JIN. Transformation Process of Sodium Tungstata and Natural Graphite in Argon Atmosphere at High Temperature[J]. Acta Scientiarum Naturalium Universitatis Pekinensis, 2017, 53(1): 50-56.

导出引用管理器 EndNote|Ris|BibTeX

链接本文: https://xbna.pku.edu.cn/CN/10.13209/j.0479-8023.2016.052

https://xbna.pku.edu.cn/CN/Y2017/V53/I1/50

图/表 9

图1 酸洗前后天然土状石墨的X射线衍射谱 G: 石墨; Q: 石英; S: 钙铝榴石

Fig. 1 XRD patterns of graphite before and after acidification treatment

图2 不同质量比产物的X射线衍射谱图 N: Na2WO4; G: 石墨; W: α-WC; T: α-W2C; P: β-W2C; K: 电木

Fig. 2 XRD patterns of products at different mass radio

表1 样品晶胞参数精修结果与标准值α-WC对比

Table 1 Comparison of cell parameters between the samples and the standard Tungsten Cabide (α-WC)

样品编号	晶胞参数
样品编号	a/Å	c/Å	V/Å³
GN4	2.9017	2.8269	20.6132
GN3	2.9050	2.8338	20.7111
GN2	2.9057	2.8354	20.7321
NG1	2.9025	2.8285	20.6364
NG2	2.9028	2.8294	20.6466
NG3	2.9100	2.8297	20.7522
NG4	2.9025	2.8334	20.6720
NG5	2.9020	2.8336	20.6671
NG6	2.9019	2.8337	20.6655
α-WC*	2.9063	2.9063	20.8000

表2 样品晶胞参数精修结果和标准值α-W2C对比

Table 2 Comparison of cell parameters between the samples and the standard Tungsten Cabide (α-W2C)

样品编号	晶胞参数
样品编号	a/Å	c/Å	V/Å³
GN6	2.9981	4.7286	36.8084
GN5	3.0016	4.7336	36.9334
GN4	2.9994	4.7317	36.8639
GN3	3.0015	4.7342	36.9356
GN2	3.0016	4.7359	36.9511
NG1	3.0012	4.7352	26.9363
NG2	3.0019	4.7347	36.9502
NG3	3.0010	4.7332	36.9160
NG4	3.0004	4.7337	36.9042
α-W₂C*	2.9970	4.7279	36.8000

表3 样品晶胞参数精修结果和标准值β-W2C对比

Table 3 Comparison of cell parameters between the samples and the standard Tungsten Cabide (β-W2C)

样品编号	晶胞参数
样品编号	a/Å	b/Å	c/Å	V/Å³
GN6	4.7210	6.0300	5.1799	147.4594
GN4	4.7213	6.0285	5.1800	147.4597
GN2	4.7220	6.0297	5.1786	147.4602
GN1	4.7212	6.0316	5.1796	147.4599
NG2	4.7209	6.0299	5.1793	147.4588
NG4	4.7215	6.0300	5.1799	147.4598
NG6	4.7210	6.0299	5.1800	147.4591
β-W₂C*	4.7210	6.0300	5.1800	147.4600

图3 α-WC与α-W2C结晶强度的关系 WCH表示α-WC的结晶强度, W2CH表示α-W2C的结晶强度, cts为XRD拟合分析的强度单位

Fig. 3 Relationship of crystal intensity between α-WC and α-W2C

图4 不同质量比产物的α-WC和α-W2C结晶强度比值的关系

Fig. 4 α-WC and α-W2C crystal intensity ratio at different mass radio

图5 样品GN5 (a)、Na2WO4 (c)和石墨(d)的SEM图像及(b)中A和B点的EDS图谱((b)为(a)中框选区域)

Fig. 5 SEM image of sample GN5 (a), Na2WO4 (c) and graphite (d) and EDS spectra of points A and B of (b)

图6 石墨与钨源接触界面反应示意图

Fig.6 Contact interface reaction of graphite and tungsten source

参考文献 18

[1]	张忠健, 龙坚战. 碳化钨/金属间化合物硬质合金的研究进展. 硬质合金, 2012(6): 378‒386
[2]	任莹, 王晓燕, 陈小凡. 钨粉与碳化硅为原料制备碳化钨陶瓷涂层的组织及耐磨性研究. 陶瓷, 2013 (4): 24‒27
[3]	Levy R B, Boudart M. Platinum-like behavior of tungsten carbide in surface catalysis. Science, 1973, 181: 547‒549
[4]	Shao G, Guo J, Xie J, et al. The preparation of CoWO4/WO3 nanocomposite powder. Journal of Wu-han University of Technology-Mater, Sci Ed, 2004, 19(2): 1‒3
[5]	柳林, 李兵, 丁星兆, 等. 机械合金化法制备超高熔点金属碳化物纳米材料. 科学通报, 1994(5): 471‒474
[6]	罗崇玲, 易茂中, 谭兴龙, 等. 新型直接碳化法制备超细WC粉及其烧结体的结构与性能. 粉末冶金技术, 2007(4): 243‒246
[7]	熊仁金, 周大利, 胡驰, 等. 溶胶凝胶‒原位碳化法制备纳米碳化钨及Pt/WC复合催化性能. 中国科技论文在线, 2011, 6(2): 125‒130
[8]	钟海云, 李荐, 戴艳阳, 等. 纳米碳化钨粉的研究及应用开发动态. 稀有金属与硬质合金, 2001(2): 44‒48
[9]	李继刚, 吴希俊, 谭洪波, 等. 纳米碳化钨粉的制备及其热稳定性研究. 稀有金属材料与工程, 2004, 33(7): 736‒739
[10]	Gao L, Kear B H. Synthesis of nanophase WC powder by a displacement reaction process. Nanostructured Materials, 1997, 9: 205‒208
[11]	高勇, 唐振方, 黄景清, 等. 纳米 WC-Co 复合材料制备及其烧结过程. 硬质合金, 2000, 17(1): 18‒20
[12]	徐志花, 马淳安, 甘永平. 超细碳化钨及其复合粉末的制备. 化学通报, 2003(8): 544‒548
[13]	Keller V, Wehrer P, Garin F, et al. Catalytic activity of bulk tungsten carbides for alkane reforming. 2. Catalytic activity of tungsten carbides modified by oxygen. Journal of Catalysis, 1997, 166(2): 125‒135
[14]	高天明, 陈其慎, 于汶加, 等. 中国天然石墨未来需求与发展展望. 资源科学, 2015, 37(5): 1059‒ 1067
[15]	梁雄, 李亚伟, 张雨, 等. 提纯土状石墨对铝碳材料显微结构和力学性能的影响. 硅酸盐学报, 2014, 42(3): 357‒365
[16]	刘士军, 陈启元, 张平民, 等. 仲钨酸钠的热分解研究. 物理化学学报, 1998, 14(9): 821‒825
[17]	Welham N J. Novel route to submicrometer tungsten carbide. Aiche Journal, 2000, 46(1): 68‒71
[18]	Pearson K. Notices respecting new books. Tables for statisticians and biometricians. Philosophical Maga-zine, 1916, 31: 493‒495