热处理对激光选区熔化成型纯钛钛瓷结合强度的影响

Effects of heat treatment on the bonding strength of pure titanium processed via selective laser melting and porcelain

目的探讨热处理对激光选区熔化(selective lasermelting,SLM)成型纯钛钛瓷结合强度的影响。方法利用SLM技术制作ISO 9693标准要求的纯钛试件96个,分为热处理组(A)和未热处理组(B)。A、B组试件根据瓷粉种类分为Super Ti22(a)、Titankeramik(b)、Triceram(c)组。再根据喷砂压力0.25 MPa(1),0.45 MPa(2),最终分为Aa1、Aa2、Ab1、Ab2、Ac1、Ac2及Ba1、Ba2、Bb1、Bb2、Bc1、Bc2组。使用激光扫描共聚焦显微镜观察喷砂试件表面形貌及测量粗糙度;烤瓷后测试三点弯曲钛瓷结合强度;使用体视显微镜观察瓷层剥脱后的钛表面形貌并分析其断裂模式。结果A组维氏硬度(188.21±11.94)HV低于B组维氏硬度(204.48±6.32)HV(P<0.05)。粗糙度值A1组(2.90±0.32)μm,A2组(3.43±0.43)μm,差异有统计学意义(P<0.05);B1组(2.62±0.08)μm,B2组(3.01±0.06)μm,差异有统计学意义(P<0.05)。A组结合强度均高于B组[Aa1组(33.75±2.31)MPa,Aa2组(36.32±1.44)MPa,Ab1组(39.82±2.28)MPa,Ab2组(33.74±1.53)MPa,Ac2组(38.63±1.36)MPa;Ba1组(29.65±1.10)MPa、Ba2组(27.17±2.24)MPa、Bb1组(27.29±1.61)MPa、Bb2组(23.85±0.97)MPa、Bc2组(35.75±1.93)MPa(P<0.05)];随着喷砂压力的增大,钛瓷结合强度Aa2组高于Aa1组,Ab2组低于Ab1组(P<0.05);Ba2、Bb2、Bc2组结合强度低于对应的Ba1、Bb1、Bc1组结合强度。A组及Bc1、Bc2组为混合断裂,Ba1、Ba2、Bb1、Bb2组为界面断裂。结论热处理可降低SLM纯钛的维氏硬度;SLM纯钛热处理后有利于三种瓷粉与纯钛的结合;喷砂压力对钛瓷结合强度有影响。

Objective To evaluate the effect of heat treatment on the bonding strength of pure titanium formed by selective laser melting(SLM)and porcelain.Methods Ninety⁃six pure titanium specimens were laser machined to meet ISO 9693 standards.The specimens were divided into a heat treated group(A)and a nonheat treated group(B).Ac⁃cording to the porcelain type,the specimens in groups A and B were divided into Super Ti22(a),Titankeramik(b),and Triceram(c)groups.Then,according to sandblasting pressures of 0.25 MPa(1)and 0.45 MPa(2),they were further di⁃vided into Aa1,Aa2,Ab1,Ab2,Ac1,Ac2,Ba1,Ba2,Bb1,Bb2,Bc1,and Bc2 groups.The surface morphology and roughness of the sandblasted specimens were assessed using a laser scanning confocal microscope.After the porcelain was fused,the three⁃point bending titanium⁃porcelain bonding strength was tested.A stereomicroscope was used to char⁃acterize the titanium⁃porcelain interfaces and determine the mode of failure.Results The Vickers hardness of group A specimens(188.21±11.94)was significantly lower than that of group B specimens(204.48±6.32)HV(P<0.05).The roughness value in group A1(2.90±0.32)μm was significantly lower than that in group A2(3.43±0.43)μm(P<0.05).Specimens in group B1(2.62±0.08)μm were significantly smaller than those in group B2(3.01±0.06)μm(P<0.05).The bonding strength in group Aa1 was(33.75±2.31)MPa,group Aa2 was(36.32±1.44)MPa,group Ab1 was(39.82±2.28)MPa,group Ab2 was(33.74±1.53)MPa and group Ac2 was(38.63±1.36)MPa,which was significantly higher than that in the corresponding groups Ba1(29.65±1.10)MPa,Ba2(27.17±2.24)MPa,Bb1(27.29±1.61)MPa,Bb2(23.85±0.97)MPa,and Bc2(35.75±1.93)MPa(P<0.05).With increasing sandblasting pressure,the bonding strength of the titanium ceramic in group Aa2 was significantly higher than in group Aa1,while that in group Ab2 was significantly lower than that in group Ab1(P<0.05).In groups A,Bc1 and Bc2,the fracture model showed mixed fail⁃ure,while in groups Ba1,Ba2,Bb1,and Bb2,the model showed interfacial failure.Conclusion The Vickers hardness of SLM titanium can be significantly reduced by heat treatment.SLM pure titanium after heat treatment is beneficial to combination of the three porcelain types and titanium.The titanium⁃porcelain bonding strength may be affected by sand⁃blasting pressure.