【作者】 刘杰；

【导师】 邱小明； 孙大千；

【作者基本信息】 吉林大学 ， 材料加工工程， 2009， 博士

【摘要】 本文针对Ni-Cr合金烤瓷修复体存在夹杂、缩孔、气孔和裂纹等缺陷,界面结合强度低及生物相容性等问题,通过对收集到的45个Ni-Cr合金烤瓷修复体临床失败病例进行分析,研究了烤瓷工艺参数对Ni-Cr合金与陶瓷界面组织和力学性能的影响。结果表明,当烤瓷温度T=990℃,烤瓷时间t=2.5min时,Ni-Cr合金与陶瓷界面结合致密,无裂纹、孔隙等缺陷,形成一连续反应层,此反应层具有金属与陶瓷的双重性,在Ni-Cr合金和陶瓷之间起到了过渡层的作用,减少了界面缺陷,提高了Ni-Cr合金与陶瓷的界面结合强度。通过调整烤瓷工艺参数不能从根本上解决界面结合强度低及生物相容性差等技术难题。综合考虑材料的热膨胀系数以及生物相容性等,在获得适当的烤瓷工艺参数烤瓷温度T=990℃,烤瓷时间t=2.5min的研究基础上,采用磁控溅射技术,在Ni-Cr合金表面分别溅射生物性良好的Ti、Zr、Au和TiN中间层,对Ni-Cr合金与陶瓷连接进行了系统的研究。结果表明,采用Ti中间层时,Ni-Cr/Ti/瓷界面结合致密,界面无裂纹、孔隙等缺陷。Ni-Cr/Ti/瓷界面反应非常复杂,界面形成的新物相有SnCr0.14OX、NiCr2O4、Cr2O3、TiO2和Ti2Ni等。当烤瓷温度T=990℃,烤瓷时间t=2.5min,Ti中间层厚度为3μm时,Ni-Cr/Ti/瓷界面结合强度可达到48.4MPa,与Ni-Cr/瓷界面的结合强度比较提高了20.4%。应用热力学和键参数理论,揭示了Ni-Cr/Ti/瓷界面的反应机制。高温烤瓷过程中,Ti与Ni以稳定的化合物Ti2Ni形式结合,同时Ti与陶瓷中Al2O3反应生成AlTi3化合物,与SnO2和SiO2发生置换反应生成TiO2,TiO2与陶瓷中氧化物结合,更好的实现了Ni-Cr合金与陶瓷的连接。Ni-Cr合金表面溅射Ti中间层后本身对离子析出具有一定的屏蔽作用;Ti与Ni形成稳定的化合物进一步阻碍离子析出;Ti与瓷界面反应生成的TiO2层具有较好的耐腐蚀性能,并且TiO2层破损后具有很好的自修复能力,对抑制Ni-Cr合金的离子析出具有持续性。采用大型有限元分析软件ALGOR建立三维有限元模型,分析了Ni-Cr合金与陶瓷界面连接残余应力的大小和分布,对修复体结构进一步优化。将上述研究融于一体,在提高金/瓷界面结合强度、降低界面残余应力和提高Ni-Cr合金的耐腐蚀性三个关键性的技术瓶颈实现了突破,为提高Ni-Cr合金烤瓷修复体质量提供了可靠而详实的试验依据。更多还原

【Abstract】 Porcelain fused to metal restorations is sintered with dental porcelain material (mixing multiple porcelain into porcelain slurry) on the metal or alloy matrix under the vacuum condition. Virtually, it is a material bonded by metal and porcelain. Ni-Cr alloy can make the alloy crown thinner by its lower price, high elasticity and strength as well as reducing natural teeth abrasion when repairing absent or defect teeth. So Ni-Cr alloy is popular with doctors and sufferers and takes a main position in domestic metal of porcelain firing restorations. There are much difference in the performance parameters between Ni-Cr alloy and porcelain, these are: different chemical bond and it is difficult to bond better with metallurgy combination or bonding; Different thermal expansion coefficient and there are larger residual stress easily producing at the interface; Lower thermal shock resistance property of porcelain, etc. and these are taking more difficulties to making Ni-Cr alloy restorations. Therefore, it has a deeply theoretical value on discovering the mechanism of action between Ni-Cr alloy and the oxide of dental porcelain, studying the effects of interface products category, quantity and distribution on the bonding strength of metal/porcelain interface, lowing porcelain bursting and cracking due to the higher residual stress at the interface resulted in by the different thermal expansion coefficient between metal and porcelain, exploring the new restoration making technology and improving the development of crossing subjects.This article studies the critical desiderating problems to solve about the Ni-Cr alloy restorations which taking a main place in domestic dental repairing area through investigating the situations in several domestic dental hospitals and reading relating reference documents. Appearance characters, cause of formation and harm of the defects of Ni-Cr alloy restorations have been studied through analyzing the made Ni-Cr alloy restorations and the collected failed restorations from clinic. The defects, such as impurity, shrinkage cavity, pores, cracks, etc., generally exit in Ni-Cr alloy restorations, the processing measures have been put forward to reduce the defects inner Ni-Cr alloy restorations and offer the technical basis to improve the quality of Ni-Cr alloy restorations.Mechanical properties and changing rules of Ni-Cr/porcelain have been studied through changing processing parameters. The results show that the interface reaction is much complicated and the new generating phase at interface is SnCr0.14OX. In definite range, as the increasing of the firing temperature and extending of the firing time, the quantity of inter-dissolving and inter-diffusing between Ni-Cr alloy and porcelain increase and the reaction layer widens, the type of metal/porcelain interface changes from diffusing type to mixed type of diffusing and compounding which has an important effect on the bonding strength of metal/porcelain interface. When firing temperature is T=990℃and firing time is t=2.5min, the shear strength is 43.8 MPa of Ni-Cr/porcelain interface and the three point bending bonding strength is 40.2 MPa.Reaction mechanism of Ni-Cr/porcelain interface is discovered after thermal theoretical calculation as well as test results. The reaction at Ni-Cr/porcelain interface is a composite oxide producing course by NiO, Cr2O3, etc. produced from oxidizing reaction at Ni-Cr alloy surface and the oxides in porcelain. The composite oxide mainly is SnCr0.14OX in interfacial reaction layer. There is less difference between the electronegativity, so composite oxides SnCr0.14OX can be looked as an aggregation by two kinds of metallic ions and oxyanion and it qualifies with metallicity and porcelain character, which can react as a transition layer between Ni-Cr alloy and porcelain. The composite oxides mixing with other oxides at the interface forms a Ni-Cr/porcelain interface reaction layer and realize to bond Ni-Cr alloy with porcelain.Systemic study has been done on the influence of Ti, Zr, Au and TiN interlayer to the microstructure and property of Ni-Cr alloy/porcelain interface. The design for interlayer is extremely important. Under the effect of interlayer, the bonding of Ni-Cr /porcelain interface translates into the bonding of Ni-Cr/interlayer/porcelain interface. Selection of interlayer should consider the products formed from interaction between Ni-Cr alloy and porcelain to be good to interface bonding, improve anti-corrosion property of Ni-Cr alloy, adjust the thermal action of Ni-Cr alloy and porcelain, ensure the instant thermal stress and residual stress being lower and qualifying with suitable direction during the course of cooling and avoid immediate or overdue porcelain bursting and cracking.When using Ti interlayer, Ni-Cr/Ti/porcelain interface bond compactly without cracks and holes, etc.. The reaction is complicated at Ni-Cr/Ti/porcelain interface, and the new forming phases at interface are SnCr0.14OX, NiCr2O4, Cr2O3, TiO2, AlTi3 and Ti2Ni. When firing temperature is T=990℃, firing time is t=2.5min and thickness of Ti interlayer is 3μm, bonding strength of Ni-Cr/Ti/porcelain interface is 48.4 MPa, which is improved 20.4% compared with Ni-Cr/porcelain interface.Pores, cracks, etc. exit on near porcelain side of Ni-Cr/Zr/porcelain interface with Zr interlayer. Products of reaction at Ni-Cr/Zr/porcelain interface are SnCr0.14OX, ZrO2 and Al3Zr. When firing temperature is T=990℃, firing time is t=2.5min and thickness of Zr interlayer is 3μm, the bonding strength of Ni-Cr/Zr/porcelain interface is 41.5 MPa, so there is a little bonding strength improving with Zr interlayer.When using Au interlayer, Ni-Cr/Au/porcelain interface bond compactly, porcelain embeds in dimples on Ni-Cr matrix caused by sandblasting and both interlock together. Products of reaction at Ni-Cr/Au/porcelain interface are SnCr0.14OX and Cr2O3 and there is no Au compound being detected. When firing temperature is T=990℃, firing time is t=2.5min and thickness of Au interlayer is 1μm, the bonding strength of Ni-Cr/Au/porcelain reaches 51.1 MPa. The bonding strength increases 25.2% compared with Ni-Cr/porcelain interface.When using TiN interlayer, the Ni-Cr/TiN/porcelain is clear and bond compactly, and there are no defects of cracks, gaps, etc. and the N2/Ar flow ratio has less effect on interface microstructure. Products of reaction at Ni-Cr/TiN/porcelain interface are SnCr0.14OX, TiO2 and Cr2O3; Interface bonding strength is different with different N2/Ar flow ratio. When N2/Ar flow ratio is 1/3, the bonding strength of Ni-Cr/TiN/porcelain reaches 47.8 MPa. The bonding strength increases 18.9% compared with Ni-Cr/porcelain interface.The sequence of interface bonding strength from low to high is Zr<TiN<Ti<Au when using different interlayer. The bonding strength with Ti and TiN interlayer is little different. The anti-corrosion property of Ni-Cr alloy has been improved with Ti, Au and TiN interlayer. Metal ions of Ni, Mo, Be, etc. separate out from Ni-Cr alloy in artificial saliva. Gross quantity of metal ions and all kinds of ions concentration decrease when sputtering Ti and TiN interlayer on Ni-Cr alloy surface comparing with that before sputtering. Specially, it has a screen effect on ion stripping after sputtering Ti interlayer on Ni-Cr alloy surface; Stable compound formed by Ti and Ni prevents the ion stripping further. TiO2 produced from the reaction between Ti and porcelain interface qualifies with a good anti-corrosion property and thinner TiO2 layer has a better self-repairing capability after damage which has a continuously restricting effect on ion stripping.Reaction mechanism of Ni-Cr/Ti/porcelain interface is discovered applying thermodynamics and bond parameter theory. During the high temperature firing, stable Ti2Ni compound is the bond Ti and Ni and AlTi3 compound produced by the reaction between Ti and Al2O3 in porcelain, TiO2 produced by the displacement reaction between Ti and SnO2, SiO2, etc., then TiO2 reacts with the oxides in porcelain and exits with sosoloid mode. Ti interlayer reacts with porcelain as well as Ni-Cr alloy during high temperature firing after sputtering Ti interlayer on Ni-Cr alloy surface which can realize the bond Ni-Cr with porcelain.Residual stress and its distribution on Ni-Cr/porcelain bonding are simulated with finite element analysis method and larger residual stress value appears in a narrow area on the near porcelain side. Residual stress and distribution position of Ni-Cr/Ti/porcelain has been improved when using Ti interlayer comparing with the residual stress of Ni-Cr/porcelain interface and inner stress of Ni-Cr alloy and porcelain has been released and the residual stress is transferred to Ti interlayer; The thickness of Ti interlayer has effects on residual stress. As the thickness of Ti interlayer increasing, theσzof interface is increasing and shearing stressτzxis little different.更多还原