异种金属间激光焊接的初步研究

目的:通过对焊件机械强度的测定及熔合区微观结构的分析,探讨口腔常用合金异种金属间激光焊接的可行性。方法:采用钴铬合金、镍铬合金、纯钛进行异种金属间的激光焊接,测定焊件的最大抗拉、抗弯强度,并进行拉伸断口的扫描电镜观察和熔合区的金相分析,探讨激光焊接异种金属的焊接质量及临床应用的可行性。结果:钴铬和镍铬合金异种金属间的激光焊件机械性能较好,钴铬焊丝组和镍铬焊丝组在最大抗拉、抗弯强度上无显著差异(P>0.05)。纯钛与钴铬或者镍铬合金激光熔接接头脆性大,断面可见严重的裂纹和气孔。结论:钴铬合金与镍铬合金异种合金间的激光焊接,不管采用钴铬焊丝或者镍铬焊丝,都可获得良好的焊接接头。纯钛与钴铬合金或者镍铬合金都不能采用激光直接进行熔接     

激光功率对钴铬合金及镍铬合金焊件机械性能的影响

目的:探讨不同激光功率对钴铬合金、镍铬合金焊件机械性能的影响。方法:采用临床上最常用的的2种合金进行不同功率的激光焊接,通过测定焊件的机械强度,并进行断口扫描电镜观察、熔合区金相分析和显微硬度测试,研究激光功率与焊件强度的关系。结果:钴铬合金焊件随着激光功率的增大,最大抗拉强度增大,抗弯强度则有下降的趋势;镍铬合金4组试件的最大抗拉、抗弯强度无显著差异;微观显示随着功率的增大,裂纹和气孔有增多的趋势;熔合区的显微硬度比母材高,随着功率的增大,显微硬度增大的区域增宽。结论:合适的激光功率是取得理想激光焊接接头的关键。     

两种热处理方式对激光焊接钴铬-镍铬异种合金力学性能和组织结构的影响

探讨常规热处理和烤瓷对激光焊接钴铬-镍铬异种合金力学性能和组织结构的影响,以期为异种合金的临床应用提供参考.方法将0.5 mm厚的钴铬合金和镍铬合金试件各15个从中间断开,进行激光焊接,制成30个钴铬-镍铬异种合金焊件.焊后用随机数字表将焊件随机分为3组,每组10个.对照组不做处理,热处理组焊件进行常规热处理,烤瓷组焊件进行烤瓷处理.测试3组焊件的拉伸强度和延伸率,扫描电镜观察拉伸断口,能谱分析测试3组焊件熔焊区、钴铬焊接交界区和镍铬焊接交界区元素.结果经热处理和烤瓷处理后,焊件拉伸强度分别为(537.15±43.91)MPa和(534.58±48.47)MPa,延伸率分别为(7.65±0.73)%和(7.40±0.45)%.烤瓷组拉伸断口出现明显的韧窝结构,热处理组拉伸断口表现为深而大的韧窝;钴铬侧合金成分向熔焊区和镍铬侧有一定程度的扩散,热处理组比烤瓷组扩散更明显.结论热处理和烤瓷过程均可在一定程度上改善激光焊接钴铬-镍铬异种合金焊接接头的性能,热处理对焊接接头性能的改善比烤瓷更明显.     

常用牙科合金与铁铬钼软磁合金激光焊接件的拉伸性能评价

目的:评价激光焊接常用牙科合金与铁铬钼软磁合金后的拉伸性能.方法:铸造钴铬合金、镍铬合金拉伸试件,随机分组并分别与铁铬钳软磁合金试件用激光焊接机焊接,以激光焊接同种钻铬合金拉伸试件为对照组.利用万能拉伸试验机测试焊接后试件的抗拉强度、0.2%屈服强度,利用扫描电镜分析断裂口,并分别进行比较.结果:激光焊接铁铬钼软磁合金与钴铬合金、镍铬合金的扰拉强度、0.2%屈服强度与激光焊接同种钴铬合金无统计学差别.激光焊接铁铬钼合金与镍铬合金的断裂口呈韧件断裂,激光焊接铁铬钼合金与钴铬合金的断裂口呈韧性-解理混合型断裂,而激光焊接钻铬合金的断口呈准解理断裂.结论:从拉伸性能方面考虑,激光焊接铁铬铜软磁合金与钴铬合金、镍铬合金可应用于磁性固位体构件的焊接.     

3种全冠修复材料对牙龈指数的影响

目的研究全瓷冠、镍铬合金烤瓷冠、钴铬合金烤瓷冠修复对患牙牙龈指数的影响。方法 100例接受全冠修复的患者共155件修复体,按修复材料分为3组,镍铬合金烤瓷组62件,钴铬合金烤瓷组50件,全瓷组43件。于修复前、修复后6个月、修复后12个月分别检测3组患牙的牙龈指数,并进行统计学分析。结果修复前、修复后6个月、修复后12个月镍铬合金烤瓷组牙龈指数分别为0.81±0.27、1.71±0.23、1.73±0.30,钴铬合金烤瓷组分别为0.80±0.25、0.79±0.20、0.89±0.20,全瓷组分别为0.83±0.33、0.78±0.29、0.89±0.32。镍铬合金烤瓷组、钴铬合金烤瓷组在修复前、修复后6个月、修复后12个月的牙龈指数呈升高趋势,差异有统计学意义(P<0.05)。全瓷组在3个时间点牙龈指数变化无统计学意义。结论全瓷冠随着时间变化,牙龈指数升高不明显,对牙龈组织的刺激小,临床效果更为优良,有利于牙周健康的维护。     

3种临床常用烤瓷合金对小鼠成纤维细胞L929的毒性评价

目的:评价3种临床常用牙科烤瓷合金材料的细胞毒性.方法:采用一种能快速评定细胞增殖率和细胞毒性的CCK-8比色法,检测镍铬合金(Ni,77.36%)、钴铬合金(Co,61.0%)、金合金(Au,58.0%)等3种烤瓷合金材料对小鼠成纤维细胞L929相对增殖率的影响;应用单细胞凝胶电泳(彗星电泳),检测3种烤瓷合金材料对小鼠成纤维细胞L929 DNA的损伤情况.采用SAS9.0软件包对数据进行统计学分析.结果:镍铬合金组、钴铬合金组和金合金组细胞的相对增殖率分别为(75.9510±7.6244)%、(84.8920±8.2660)%和(88.5420±12.3611)%.镍铬合金组的细胞毒性显著高于钴铬合金组(P＜0.05)和金合金组(P＜0.05),而钴铬合金组与金合金组之间无显著差异(P＞0.05),但3种材料的细胞毒性分级均为1级,表现为轻微毒性;镍铬合金组DNA损伤程度的彗星数目显著高于钴铬合金组(P＜0.05)和金合金组(P＜0.05).而钴铬合金组与金合金组无显著差异(P＞0.05).结论:钴铬烤瓷合金材料的细胞毒性显著低于镍铬烤瓷合金材料,而与58%金烤瓷合金材料的细胞毒性接近.临床上应尽可能选择钴铬烤瓷合金或58%金烤瓷合金等细胞毒性较低的烤瓷合金材料.     

镍铬合金、钴铬合金和纯钛金瓷结合强度的比较

目的比较镍铬合金、钴铬合金和纯钛的金瓷结合强度和金瓷界面特征。方法执行ISO9693[1]标准,采用三点弯曲试验分别测定在常规热处理条件下的镍铬合金、钴铬合金和纯钛的金瓷结合强度。运用扫描电镜和X射线衍射进行金瓷界面分析。结果金瓷结合强度分别为:镍铬合金:(37.56±2.92)Mpa,钴铬合金:(39.06±2.79)Mpa,纯钛:(32.61±5.62)Mpa,前两者组间差异无统计学意义(P>0.05),后者与前两者组间差异有统计学意义(P<0.05)。扫描电镜和X线衍射:镍铬合金和钴铬合金与瓷之间紧密接触,无裂纹,界面过渡层15～20μm。纯钛与瓷过渡层80μm,可见孔洞。纯钛基体表面可见约2μm黑色带。结论①钴铬合金与镍铬合金的金瓷结合强度接近,都大于纯钛的金瓷结合强度。②钴铬合金、镍铬合金、纯钛的金瓷结合强度都大于25Mpa,按ISO9693标准均可应用于临床。③金瓷之间存在结合介质,形成过渡层。     

三种非贵金属合金常规研抛后的超微结构表面特征研究

目的:试验观察3种非贵金属合金经临床常规使用的机械法研抛后的超微结构表面特征,为临床合理选择材料提供实验依据,并为非贵金属改性提供合理有效的超微结构理论依据。方法:采用镍铬合金、钴铬合金、维他灵(VITALLIUM,钴铬钼合金)3种非贵金属合金作为试验对象,制成15mm×l5mm×2mm的试件,经过喷砂、橡胶轮加毡轮加抛光膏抛光机械法研抛处理后,分别在扫描电子显微镜下,观察镍铬合金、钴铬合金,维他灵的表面形貌,并在原子力显微镜下,观察3种合金的表面形貌和3D图像以及粗糙度。结果:扫描电镜、原子力显微镜结果显示3种非贵金属合金经喷砂及抛光处理后其粗糙度为喷砂组:镍铬合金(463.83±65.17)>钴铬合金(336±146.04)>维他灵2000(303±139.10);抛光组:镍铬合金(15.95±4.55)>钴铬合金(9.17±2.58)>维他灵2000(9.15±2.69)。镍铬合金>钴铬合金>维他灵。镍铬合金3D图像形貌明显、立体感强,钴铬合金较平坦,维他灵平坦。结论:SEM及AFM下,形貌平坦程度:镍铬合金<钴铬合金<维他灵,AFM与常规SEM相比,图像分辨率清晰,操作简便。     

激光功率对纯钛焊件机械性能的影响

目的:研究激光功率对纯钛焊件机械性能的影响,为临床应用激光焊钛提供参考。方法:采用3种不同的激光功率对纯钛进行焊接,通过测定焊件的机械强度,并进行断口扫描电镜观察和熔合区金相分析,研究激光功率与焊件强度的关系。结果:纯钛1.4kW组焊件未焊透,1.6kW和1.8kW组焊件在最大抗拉、抗弯强度上无显著差异;微观分析显示焊接接头有裂纹和气孔,以气孔为主,并且随着功率的升高,裂纹和气孔有加重的趋势。结论:激光焊接纯钛时,不能单纯以提高功率来增加熔深,避免采用过大的焊接功率。     

3种常用金属基底冠的边缘适合性评价

目的:评价高金合金、钴铬合金及镍铬合金3种不同金属基底冠的边缘适合性。方法:制作下颌第一磨牙全冠牙体制备标准金属代型1个,复制并灌注石膏模型后,制作高金合金、钴铬合金、镍铬合金基底冠各10个,依次将其就位于金属标准代型上。在体式显微镜下,对基底冠边缘与金属代型肩台之间的适合度进行观察,用CCD进行成像,并用专业图像测量软件测量边缘缝隙宽度。最后计算各组10个样本的平均值,采用SPSS11.5软件包对数据进行统计学处理。结果:高金合金、钴铬合金和镍铬合金的平均边缘缝隙宽度分别为(72.9±29.3)、(85.9±33.0)和(94.1±44.9)μm,3组之间差异显著;其中,高金合金的边缘缝隙宽度显著小于钴铬合金(P<0.01)和镍铬合金(P<0.001),而钴铬合金基底冠边缘缝隙宽度显著小于镍铬合金(P<0.05)。结论:3种瓷熔附金属基底冠的边缘适合度均在临床可接受范围,而高金合金基底冠的边缘适合度显著高于其他2种合金。     

Comparative analysis of the fit of 3-unit implant-supported frameworks cast in nickel-chromium and cobalt-chromium alloys and commercially pure titanium after casting, laser welding, and simulated porcelain firings

This study compared the vertical misfit of 3-unit implant-supported nickel-chromium (Ni-Cr) and cobalt-chromium (Co-Cr) alloy and commercially pure titanium (cpTi) frameworks after casting as 1 piece, after sectioning and laser welding, and after simulated porcelain firings. The results on the tightened side showed no statistically significant differences. On the opposite side, statistically significant differences were found for Co-Cr alloy (118.64 microm [SD: 91.48] to 39.90 microm [SD: 27.13]) and cpTi (118.56 microm [51.35] to 27.87 microm [12.71]) when comparing 1-piece to laser-welded frameworks. With both sides tightened, only Co-Cr alloy showed statistically significant differences after laser welding. Ni-Cr alloy showed the lowest misfit values, though the differences were not statistically significantly different. Simulated porcelain firings revealed no significant differences.     

Comparison of the bond strength of laser-sintered and cast base metal dental alloys to porcelain

OBJECTIVE: The purpose of this study was to compare shear bond strengths of cast Ni-Cr and Co-Cr alloys and the laser-sintered Co-Cr alloy to dental porcelain. METHODS: Dental porcelain was applied on two cast and one laser-sintered base metal alloy. Ten specimens were prepared for each group for bond strength comparison. ANOVA followed by Tukey HSD multiple comparison test (alpha=0.05) was used for statistical analysis. Fractured specimens were observed with a stereomicroscope to classify the type of failure after shear bond testing. RESULTS: While the mean shear bond strength was highest for the cast Ni-Cr metal-ceramic specimens (81.6+/-14.6MPa), the bond strength was not significantly different (P>0.05) from that for the cast Co-Cr metal-ceramic specimens (72.9+/-14.3MPa) and the laser-sintered Co-Cr metal-ceramic specimens (67.0+/-14.9MPa). All metal-ceramic specimens prepared from cast Ni-Cr and Co-Cr alloys exhibit a mixed mode of cohesive and adhesive failure, whereas five of the metal-ceramic specimens prepared from the laser-sintered Co-Cr alloy exhibited the mixed failure mode and five specimens exhibited adhesive failure in the porcelain. CONCLUSIONS: The new laser-sintering technique for Co-Cr alloy appears promising for dental applications, but additional studies of properties of the laser-sintered alloy and fit of castings prepared by this new technique are needed before its acceptance into dental laboratory practice. SIGNIFICANCE: Laser sintering of Co-Cr alloy seems to be an alternative technique to conventional casting of dental alloys for porcelain fused to metal restorations.     

激光焊接对钛耐应力腐蚀性能影响的实验研究

目的研究激光焊接对钛耐应力腐蚀性能的影响。方法将实验组激光焊接铸钛试样焊缝区加载后浸入37℃人工唾液中,浸泡90 d。实验前、后用电子扫描电镜观察焊接试样熔区表面形貌。在万能材料实验机上作拉伸实验,测出拉伸负荷,计算抗张强度,将结果进行统计学分析。不进行应力腐蚀试验的激光焊接铸钛试样作为对照组。结果应力腐蚀试验后,激光焊接钛试件表面无变色,扫描电镜观察无腐蚀裂纹及腐蚀产物,实验组抗张强度为(657.06±54.04)MPa与对照组(609.81±37.24)MPa相比差异无显著性(P>0.05)。结论激光焊接对钛的耐应力腐蚀性能无影响。     

激光焊接不同间距钴铬合金焊件疲劳强度的研究

目的: 探讨不同焊接间距对激光焊接钴铬合金试件机械强度和疲劳强度的影响。方法: 将牙科钴铬合金铸件采用激光焊接法分别在0.00 mm、0.25 mm、0.50 mm 3种焊接间距下焊接成哑铃形试件(n=10),以未焊接组作为对照,在材料测试机上进行三点弯曲试验,记录试件的最大压应力值和疲劳强度,并对断口进行显微晶相分析。结果: 各焊接组的最大压应力值和疲劳强度均小于未焊接组(P<0.05),3个焊接组的最大压应力值差别无显著性;在焊接组中0.25 mm组具有最佳的疲劳强(P<0.05),0.00 mm组和0.50 mm的差异无显著性。结论: 激光焊接焊件之间保留一定间隙有助于提高钴铬合金焊件的疲劳强度,焊接间隙在0.25 mm左右为宜。     

齿科钴铬-镍铬合金激光焊接后耐腐蚀性评价

目的:研究激光焊接钴铬-镍铬合金的体外电化学行为及离子释出情况。方法:在体外模拟口腔环境中,测出激光焊接钴铬-镍铬合金阳极极化曲线及特征指数;检测激光焊接镍铬-钴铬合金在不同时间的离子释出情况,以钴铬合金、镍铬合金为对照。结果:钴铬合金自腐蚀电位低于镍铬合金,激光焊接钴铬-镍铬合金的自腐蚀电位、维钝电流密度、破裂电位介于前两者之间;激光焊接镍铬-钴铬合金,镍离子释出量7日后少于镍铬合金,钴离子释出量始终高于镍铬合金。结论:激光焊接钴铬-镍铬合金后,钴铬合金的阳极保护作用可减少镍铬合金镍离子释出,有助于改善镍铬合金生物相容性;激光焊接钴铬-镍铬合金,对其整体耐腐蚀性未有较大影响。     

��ͬ���ײ���������ɽ����ʵ���о�

目的比较不同基底材料与饰面瓷的结合力,为修复临床选择不同的瓷修复体提出依据。方法 2009年11月至2010年5月在大连市口腔医院应用特制模具制作基底材料标本蜡型(直径6mm,高8mm)共60个。根据各基底材料制作要求分别制作镍铬(Ni-Cr)合金、钴铬(Co-Cr)合金、金钯(Au-Pd)合金、混合Au-Pd合金、压铸瓷及氧化锆基底材料标本(每组10个)。在实验标本的一端堆瓷,瓷层总厚度控制在(2.0±0.01)mm。在万能试验机上以0.5mm/min的加载速度进行加载至剪切断裂。对实验标本的剪切强度进行单因素方差分析。结果 6种瓷修复体的的剪切强度为:Au-Pd合金组(51.56±8.93)MPa,Ni-Cr合金组(45.61±3.11)MPa,Co-Cr合金组(37.12±4.08)MPa,混合金钯合金组(36.07±5.42)MPa,氧化锆组(31.52±7.45)MPa,压铸瓷组(29.62±9.97)MPa。单因素方差分析表明不同金属合金基底材料与饰面瓷间的剪切强度差异有统计学意义(P<0.01)。结论不同基底材料与饰面瓷的剪切强度存在差异。Au-Pd合金和Ni-Cr合金与饰面瓷结合力强。     

Structure and mechanical properties of Cresco-Ti laser-welded joints and stress analyses using finite element models of fixed distal extension and fixed partial prosthetic designs

STATEMENT OF PROBLEM: The Cresco-Ti System uses a laser-welded process that provides an efficient technique to achieve passive fit frameworks. However, mechanical behavior of the laser-welded joint under biomechanical stress factors has not been demonstrated. PURPOSE: This study describes the effect of Cresco-Ti laser-welding conditions on the material properties of the welded specimen and analyzes stresses on the weld joint through 3-dimensional finite element models (3-D FEM) of implant-supported fixed dentures with cantilever extensions and fixed partial denture designs. MATERIAL AND METHODS: Twenty Grade III (ASTM B348) commercially pure titanium specimens were machine-milled to the dimensions described in the EN10002-1 tensile test standard and divided into test (n = 10) and control (n = 10) groups. The test specimens were sectioned and laser-welded. All specimens were subjected to tensile testing to determine yield strength (YS), ultimate tensile strength (UTS), and percent elongation (PE). The Knoop micro-indentation test was performed to determine the hardness of all specimens. On welded specimens, the hardness test was performed at the welded surface. Data were analyzed with the Mann-Whitney U test and Student's t test (alpha=.05). Fracture surfaces were examined by scanning electron microscopy to characterize the mode of fracture and identify defects due to welding. Three-dimensional FEMs were created that simulated a fixed denture with cantilever extensions supported by 5 implants (M1) and a fixed partial denture supported by 2 implants (M2), 1 of which was angled 30 degrees mesio-axially. An oblique load of 400 N with 15 degrees lingual-axial inclinations was applied to both models at various locations. RESULTS: Test specimens fractured between the weld and the parent material. No porosities were observed on the fractured surfaces. Mean values for YS, UTS, PE, and Knoop hardness were 428 +/- 88 MPa, 574 +/- 113 MPa, 11.2 +/- 0.4%, 270 +/- 17 KHN, respectively, for the control group and 642 +/- 2 MPa, 772 +/- 72 MPa, 4.8 +/- 0.7%, 353 +/- 23 KHN, respectively, for the test group. The differences between the groups were significant for all mechanical properties ( P <.05). For both models, the FEA revealed that maximum principal stresses were concentrated at the framework-weld junction but did not exceed the UTS of the weld joint. CONCLUSION: Within the constraints of the finite element models, mechanical failure of the welded joint between the support and the framework may not be expected under biomechanical conditions simulated in this study.