Effect of liquid-to-solid ratios on the properties of magnesium phosphate chemically bonded ceramics Wang Aijuan, Wang Yao【推荐论文】 .doc
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1、精品论文Effect of liquid-to-solid ratios on the properties of magnesium phosphate chemically bonded ceramics Wang Aijuan, Wang Yao5(School of Material Science and Engineering, Xian University of Technology, Xian 710048) Abstract: The temperature variation, setting time, phase compositions and compressiv
2、e strength of magnesium phosphate chemically bonded ceramics were important for its application in biomedical field. Different amount of liquid were added into the premixed acid phosphates and oxides powders in order to study the effect of liquid-to-solid ratios on the properties of magnesium phosph
3、ate chemically10bonded ceramics. The results indicated that the setting time increased and the maximum temperature decreased as the increase of liquid-to-solid ratio. The hydrated product was mainly composed bymagnesium potassium phosphate hexahydrate, which was not affected by the liquid-to-solid r
4、atios. Besides, magnesia was also found because it was obvious excess for the hydrated reaction. The compressive strength decreased as the increase of liquid-to-solid ratios possibly because of the higher15porosity caused by the superfluous liquid. According to the performed study, results indicated
5、 that the properties of MPCBC could be adjusted by changing the liquid-to-solid ratios.Keywords: Inorganic material; Magnesium phosphate chemically bonded ceramics; Chemical preparation; Liquid-to-solid ratios; Biomedical applications200IntroductionBecause of the excellent adhesive strength and high
6、er early compressive strength, magnesium phosphate chemically bonded ceramics (MPCBC) attracted much attention in the field of hard tissue repair, especially for the use of artificial joints fixation, screw fixation as well as comminuted fracture fixation, etc 1-4. The solidifying process of MPCBC i
7、ncluding the25dissolution of acid phosphates (such as NH4H2PO4, NaH2PO4, KH2PO4, etc), the release of cations (Mg2+), and then PO43- reacted with the newly released Mg2+ ions. Subsequently, themain reaction product of magnesium potassium phosphate hexahydrate (MgKPO46H2O), alsowas called k-struvite,
8、 appeared. After that, a coordinated network was formed and consolidated into MPCBC 5-8. Obviously, it was necessary of the simultaneous presence of Mg2+ and PO43-30ions to form the coordinated network. The reaction equation was described as follows 9:- 9 -4Mg2+ + PO 3-+ K+ 6H2O MgKPO46H2OEq(1)Which
9、 could be also expressed as follows 10,11:MgO(s) + KH2PO4(s) + 5H2O MgKPO46H2O(s)Eq(2)It was clear that factors influencing the hydrated process and hydrated products involved35many aspects, such as the raw materials properties, liquid-to-solid (H2O/(MgO+KH2PO4) ratios, kinds of liquid, etc. Many st
10、udies on the influencing factors have been carried out by many researchers 4, 8, 12-14. For example, G. Mestres, et al.4 selected NaH2PO4, NH4H2PO4, and the equimolar mixture of both as the raw materials, and studied the change of phase compositions with different raw materials. The results indicate
11、d the NH4+-containing MPCBC resulted in40struvite (MgNH4PO46H2O) as the major reaction product, whereas MPCBC prepared with NaH2PO4 resulted in an amorphous product. The effect of water content on the mechanical properties of MPCBC, including compressive strength and elastic modulus were investigate
12、d by Z. Ding, et al 12. The results showed that the mechanical properties of MPCBC were mainlycontrolled by the total porosity which was determined by water content. F. Qiao, et al. 8 studiedFoundations: Doctoral Fund of Ministry of Education of China (No. 20106118120013);The natural sciencefoundati
13、on of Shaanxi Province(2012JQ6009)Brief author introduction:Wang Ai-juan, (1981-), female, Lecture, biomedical materials. E-mail:45the properties of MPCBC with different magnesium to phosphate (M/P) molar ratio. The experimental results showed that the M/P ratio had large influence on the setting ti
14、me and mechanical properties of MPCBC. The setting time decreased with the raised M/P ratios. Besides, as the increase of M/P ratio, the compressive strength of MPCBC increased at first and then decreased. In our previous work, the effect of raw materials properties on the solidifying process50has b
15、een carried out13. The results indicated that the setting time increased and the maximum temperature decreased as the decrease of the chemical activity of MgO. Besides, the phasecompositions were similar with each other, and mainly composed of MgO and MgKPO46H2O.From above, it could be found that ma
16、ny studies have been carried out on the influencing factors on the properties of MPCBC. As we all known, the temperature variation, setting time,55phase compositions and compressive strength of magnesium phosphate chemically bonded ceramics were important for its application in biomedical field. How
17、ever, there are relatively few studies on the above properties of MPCBC when it was used as biomedical materials. Unlike in construction cements, the cost of the end product is not a major issue when it was used as biomedical materials, but purity and performance of the final product is very importa
18、nt 7.60Therefore, the effect of liquid-to-solid ratios on the setting time, temperature variation curves, microstructures, phase compositions and compressive strength of MPCBC were characterized systematically in this article.1Material and methodsMedical grade MgO particles (Zehui Chemical Industry
19、Group, China) were calcined at 1100,651200, 1300, 1400, 1500 for 3h. Chemical reagent KH2PO4 particles (Beijing Kang Pu Hui Wei Technology Co., Ltd, China) were used as the acid compound. Deionized water was employed as the solidifying liquid. MgO-to-KH2PO4 weight ratio of 1:1 (molar ratio of about
20、3.4:1) was employed.MgO and KH2PO4 particles were mixed by milling for 3h firstly. After that, different amount70of deionized water were added into the premixed powders. Stirring was kept all the time untilMPCBC solidified. When the liquid (milliliter)-to-solid (gram) ratio was below than the value
21、of1:4 (that is 1ml liquid and 4g solid), it was difficult to shape. Besides, when the liquid-to-solid ratio was higher than the value of 2:3, the solidifying process was carried out slowly and thus caused the flow of the slurry. Therefore, based on the workability of MPCBC as chemical bonded75cerami
22、cs, the liquid-to-solid ratio was controlled with the value of 1:4, 1:3, 2:5, 1:2, 3:5, 2:3, respectively.All of the samples used to test the setting time and temperature variation were fabricated withthe mixing powders (MgO and KH2PO4) weight of 3g. The setting time of MPCBC was determined accordin
23、g to ASTM C 191 Method B with modification using an automatic Vicat80apparatus, which was described particularly in Ref.15. The temperature variation on the surface of MPCBC was tested using infrared radiation thermometer (IRT, Fluke 561) in order to indicate the heat release of the reacting process
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