Bonding interface characteristic and shear strength of diffusion bonded Ti-17 titanium alloy

The bonding interface characteristic and shear strength of diffusion bonded Ti-17 titanium alloy at different bonding time were investigated. The results show that the average size of voids decreases while the amount of voids decreases after increasing to the maximum value with the increasing bonding time. The irregular void with a scraggly edge tends to an ellipse void with smooth surface and then changes to a tiny void with round shape. The grains across bonding interface occur at bonding time of 60 min. The shear strength of bond increases with increasing bonding time, and the highest shear strength of bond is 887.4 MPa at 60 min. The contribution of plastic deformation on the void closure and the increase of shear strength is significant even though the action time of plastic deformation is short.

添加Sb对Sn-9Zn-3Bi/Cu钎料接头显微组织及力学性能的影响

采用钎料合金化研究添加Sb对Sn-9Zn-3Bi无铅焊点组织、熔点特性、润湿性、金属间化合物(IMC)厚度和剪切强度的影响。结果表明:钎料的熔点随Sb含量的增加而略微上升,钎料的铺展面积随Sb含量的增加从50.3 mm^(2)降低至36.6 mm^(2);添加Sb虽然没有改变焊点处钎料基体和界面IMC的显微组织类型,但细化了焊点显微组织,且焊点界面处的IMC厚度从18.6μm降低至16.8μm。随着钎料中Sb含量从0增加到1.5%(质量分数),Sn-9Zn-3Bi/Cu接头剪切强度从22.7 MPa增加到29.8 MPa,剪切强度的提高是显微组织细化、固溶强化及界面处IMC厚度降低共同作用的结果。

Influence of holding time on microstructure and shear strength of Mg alloy/steel joint diffusion bonded with Zn-5Al interlayer

The diffusion bonding of AZ31B Mg alloy and Q235 steel was investigated with a Zn-5Al alloy as interlayer and under different holding time ranging from 3 to 1 200 s. The microstructure and phase compositions of bonded joints were characterized by scanning electron microscopy( SEM),energy dispersive spectrometer( EDS) and X-ray diffraction( XRD)methods. The shear strength of Mg alloy/steel joints was measured by tensile tester. It was found that the microstructure of bonded joints evolved dramatically along with the prolongation of holding time. Under the holding time of 3 s,the main part of joint was composed of MgZn_2 phase and dispersed Al-rich solid solution particles. When increased the holding time more than 60 s,the excessive solution of AZ31B into the interfacial reaction area led to the formation of coarse phase and eutectic microstructure,and also the complex Fe-Al and Mg-Al-Zn IMCs at transition layer closed to Q235 steel side. According to the tensile testing characterizations,the joints obtained under holding time of 3 s exhibited the best shear strength of 84 MPa,and the fracture occurred at the intermediary part of joint where the flexible Al-rich solid solution particles could help to impede the microcrack propagations. With prolonging the holding time to 600 s,the shear strength of joints was deteriorated enormously and the fracture position was shifted to the transition layer part closed to Q235 steel.

Effect of Saliva Contamination on Shear Bond Strength of Orthodontic Brackets When Using a Self-Etch Primer

The effect of saliva contamination on the shear bond strength of orthodontic brackets, at various stages of the bonding procedure using a new self-etch primer was studied. The samples were divided into 4 groups according to 4 different enamel surface conditions: Group A: dry; Group B: saliva contamination before priming; Group C: saliva contamination after priming, and Group D: saliva contamination before and after priming. Stainless steel brackets were bonded in each test group with a light-cured composite resin (TransbondXT 3M). The shear bond strength was determined in the first 30 min after bonding. The analysis of variance indicated that the shear bond strengths of the 4 groups were significantly different (F=11.89, P<0.05). Tukey HSD tests indicated that contamination both before and after the application of the acid-etch primer resulted in a significantly lower (=4.6±1.7 MPa) shear bond strength than either the control group (=8.8±1.9 MPa) or the groups where contamination occurred either before (=7.9±2.0 MPa) or after (=6.9±1.5 MPa) the application of the primer. It was concluded that the new acid-etch primer could maintain adequate shear bond strength if contamination occurred either before or after the application of the primer. On the other hand, contamination both before and after the application of the primer could significantly reduce the shear bond strength of orthodontic brackets.

Transient liquid phase bonding of DD5 superalloy using a designed interlayer: microstructure and mechanical properties

Nickel based single crystal superalloy is currently widely used as the material for turbine blades in aerospace engines.However,metallurgical defects during the manufacturing process and damage during harsh environmental service are inevitable challenges for turbine blades.Therefore,bonding techniques play a very important role in the manufacturing and repair of turbine blades.The transient liquid phase(TLP)bonding of DD5 Ni-based single crystal superalloy was performed using the designed H1 interlayer.A new third-generation Ni-based superalloy T1 powder was mixed with H1 powder as another interlayer to improve the mechanical properties of the bonded joints.The res-ults show that,such a designed H1 interlayer is beneficial to the improvement of shear strength of DD5 alloy bonded joints by adjusting the bonding temperature and the prolongation of holding time.The maximum shear strength at room temperature of the joint with H1 interlayer reached 681 MPa when bonded at 1260℃for 3 h.The addition of T1 powder can effectively reduce holding time or relatively lower bond-ing temperature,while maintaining relatively high shear strength.When 1 wt.%T1 powder was mixed into H1 interlayer,the maximum room temperature shear strength of the joint bonded at 1260℃reached 641 MPa,which could be obtained for only 1 h.Considering the bonding temperature and the efficiency,the acceptable process parameter of H1+5 wt.%T1 interlayer was 1240℃/2 h,and the room tem-perature shear strength reached 613 MPa.

Isotropic shear bond strength behavior of superficial bovine dentin: A pilot study

The aim of this pilot study was to evaluate the shear bond strength of superficial bovine incisor dentin in different crown regions. Bonding was performed to the incisal, middle and cervical thirds of superficial bovine coronal dentin (n = 20) with a two-step etch-and-rinse adhesive (Optibond Solo Plus) and resin composite (Z100). Shear bond strength was evaluated at 24 h and failure modes of representative specimens wereobserved with FE-SEM. Non-parametric Kruskal-Wallis test with a significance level of 0.05 was used for data analysis. Mean shear bond strength values for the incisal, middle, and cervical thirds were 36.9 (3.1), 42.6 (2.6), and 37.1 (2.1) respectively with no significant differences evidenced between the crown thirds (p = 0.19). Observation of the failure mode of representative specimens demonstrated that specimens with high bond strength values exhibited predominantly mixed-type failures whereas low strength specimens exhibited adhesive failures between the dentin and adhesive. The absence of significant differences in shear bond strength between crown thirds indicate that, regardless of tubule orientation, any crown region can be used when superficial bovine incisor dentin is used for shear bond strength testing.

Shear bond strengths between alumina-toughened zirconia cores and veneering ceramics and their susceptibility to aging

Objective:To evaluate the shear bond strength(SBS) between alumina-toughened zirconia (ATZ) cores and veneering ceramics,investigate the effect of aging in artificial saliva on SBS and compare it with that of yttria-stabilized tetragonal zirconia polycrystals(Y-TZP).Methods:Bars of ATZ and Y-TZP were layered with veneering ceramics in accordance to the recommendation of the manufacturer.Half of each group(n = 10) was aged at 134℃.(under 2 bar pressure) in an autoclave for 48 h.Subsequently,all specimens were subjected to shear force in a universal testing machine.The interface and fractured surface of the specimens were evaluated using scanning electron microscopy and X-ray energy dispersive spectroscopy.Results:The initial mean SBS values in MPa±SD were 28.9±8.0 for ATZ and 26.2±7.6 for Y-TZP.After aging,the mean SBS values for ATZ and Y-TZP were 22.9±4.9 MPa and 22.8±6.9 MPa,respectively.Neither the differences between the SBS values of the ATZ and Y-TZP groups nor the influence of aging on all groups were statistically significant.Conclusions:The SBS between the ATZ core and the veneering ceramics was not affected by aging.The SBS of ATZ to veneering ceramics was not significantly different compared with that of Y-TZP.

Comparison of Two Methods of Chlorhexidine Application of Shear Bond Strength Degradation between Composite Resin and Dentin

Background: Chlorhexidine could have effect on shear bond strength of composite resin-dentin. Objective: The purpose of this study is to compare two methods of chlorhexidine application of shear bond strength degradation between composite resin and dentin. Methods: Thirty samples of dentin were taken from the crown of premolars and then divided into three groups (n = 10). Group 1 were applied bonding without chlorhexidine, group 2 were applied with liquid chlorhexidine and followed by bonding, group 3 were applied bonding which contains chlorhexidine. Each group was divided into two sub-groups (n = 5): the group with and without 10% NaOCl immersion for one hour. Then, 4 samples in each sub-group were used to measure shear bond strength using Universal Testing Machine, and 1 sample was examined with Scanning Electron Microscope (SEM). Data were analyzed using SPSS 17 by Mann-Whitney and Kruskal Wallis test. Results: The highest mean shear bond strength without 10% NaOCl immersion was in group 1, while the highest mean with 10% NaOCl immersion was in group 3. Significant differences occurred between the groups 1 and 2, groups 2 and 3. Conclusion: Method of using bonding contains chlorhexidine can increase and inhibit degradation shear bond strength between composite resin and dentin.

The Shear Bond Strengths of Composite Bonded to Dentine Following Treatment with Two Dentine Occluding Desensitizing Toothpastes

Aim: This study determined whether prior brushing with desensitizing toothpastes (Sensodyne Rapid Relief and Colgate Pro-Relief) affected the shear bond strengths of composite to dentine surfaces after appropriate use of two different dentine bonding agents (SingleBond and PQ-1). Materials and Methods: Sixty caries free molar teeth were cleaned, disinfected and embedded in individual cylinders of polymethylmethracyrlate. The occulsal surfaces were flattened to expose dentine and finished down with 600 grit silicone carbide paper. The teeth were randomly divided into six groups of 10 teeth each. Two groups served as control where dentine surfaces were brushed with pumice slurry. Of the remaining 4 groups, 2 groups were brushed with Sensodyne Rapid Relief and 2 groups brushed with Colgate Pro-Relief. The dentine surfaces were brushed to simulate 2 weeks of twice-daily toothpaste use. The specimens in each of the control groups and experimental groups were subjected to dentine bonding procedures (Single Bond or PQ-1), and application of hybrid composite resin (Z-250) according to the manufacturer’s instructions. A universal material testing machine, with a cross head speed of 0.05 mm/min was used to determine shear bond strengths. Results: Mean shear bond strengths ranged from 5.71 MPa (Colgate pretreatment, composite bonded with Single Bond) to 9.07 MPa (Sensodyne pretreatment, composite bonded with Single Bond). Results showed neither of the main effects, of toothpaste type or bonding agent were significant (p > 0.05) but their interaction was (F = 4.25, p = 0.02). Post hoc analysis showed that teeth brushed with the Sensodyne group, treated with the unfilled dentine bonding agent had a significantly higher bond strength than those treated with the filled dentine bonding agent. Conclusion: The desensitizing toothpastes that use the mechanism of occlusion of open dentinal tubules in the preliminary management of tooth sensitivity should not have an adverse effect on future restorative treatment modalities.

SBS改性沥青与石料的剪切性能

针对水煮法评价SBS改性沥青与石料间黏附性的局限性,以沥青与石料的黏结机理分析为基础,设计了基于剪切试验的沥青与石料黏附性评价方法,提出了以剪切强度作为黏附性定量评价指标,通过剪切试验,验证了剪切强度指标的可行性,分析了SBS改性剂类型、掺量和试验温度对SBS改性沥青与石料黏结作用的影响.结果表明:SBS的掺入显著改善了沥青与石料的黏结作用;随SBS掺量的增加,改性沥青与石料的黏结作用有明显的增大,当掺量为4%时,SBS改性沥青与石料的剪切强度较基质沥青提高约100%;同时,也说明剪切强度指标可定量评价沥青与石料的黏结效果,从而为改性沥青的性能评价和质量控制提供参考.

SBS改性沥青黏层抗剪性能试验研究

SBS改性沥青黏层是近年来高等级公路沥青混合料层层间结合常用材料。通过室内直剪、斜剪和拉拔试验对几种不同类型的SBS黏层材料的界面黏结性能进行了研究。试验结果显示,随温度升高,黏层抗剪强度降低,在60~70℃区间时直剪试验强度降幅为是斜剪试验的6倍。SBS改性沥青洒布量达1.8~2.0 kg/m^2时,试验抗剪强度出现峰值。保持沥青用量不变,碎石撒布量在55%时,出现抗剪强度峰值。

Study on Shear Strength Characteristics of Basalt-Concrete Bonding Interface Based on in-situ Direct Shear Test

In rock engineering,the shear strength of the basalt-concrete bonding interface is a key factor affecting the shear performance of hydroelectric dam foundations,embedded rock piles and rock bolts.In this study,30 sets of in-situ direct shear tests were conducted on the basalt-concrete bond interface in the Baihetan dam area to investigate the shear strength characteristics of the basalt-concrete bonding interface.The bonding interface contains two states,i.e.,the bonding interface is not sheared,termed as se(symbolic meaning see Table 1);the bonding interface is sheared with rupture surface,termed as si.The effects of lithology,Joints structure,rock type grade and concrete compressive strength on the shear strength of the concrete-basalt contact surface were investigated.The test results show that the shear strength of the bonding interface(s_(e)&s_(i))of columnar jointed basalt with concrete is greater than that of the bonding interface(s_(e)&s_(i))of non-columnar jointed one with the same rock type grade.When the rock type grade isⅢ_(2),fcol is 1.22 times higher than fncol and ccol is 1.13 times greater than cncol.The shear strength parameters of the basalt-concrete bonding interface differ significantly for different lithologies.The cohesion of the bonding interface(s_(i))of cryptocrystalline basalt with concrete is 2.05 times higher than that of the bonding interface(s_(i))of breccia lava with concrete under the same rock type grade condition.Rock type grade has a large influence on the shear strength of the non-columnar jointed basalt-concrete bonding interface(s_(e)&s_(i)).cnol increases by 33%when the grade of rock type rises fromⅢ_(1)toⅡ_(1).the rock type grade has a greater effect on bonding interface(s_(i))cohesion than the coefficient of friction.When the rock type grade is reduced fromⅢ_(2)toⅢ_(1),f_(ncol)′increases by 2%and c_(ncol)′improves by 44%.The shear strength of the non-columnar jointed basalt-concrete bonding interface(s_(e)&s_(i))increases with the increase of the compressive strength of concrete.When concrete compressive strength rises from 22.2 to 27.6 MPa,the cohesion increases by 94%.

SBS改性乳化沥青黏层材料的剪切性能

为了解决安徽地区沥青路面层间黏结性能差的问题,防止发生拥包、推移等病害,通过研究4种不同黏层材料(SBS、SBR改性乳化沥青、普通乳化沥青和热沥青)的抗剪强度,评价不同黏层材料的性能。结果表明:4种材料中,SBS改性乳化沥青黏层材料的抗剪性能较好,且其涂布量为0.8kg·m^(-2)左右时层间抗剪效果最佳。

Numerical Determination of Shear Strength of Steel Reinforced Concrete Column Strengthened by CFRP Sheets

The earthquake resistant property of reinforced concrete members depends on the interaction between reinforcing bars and surrounding concrete through bond to a large degree. In this paper a general system aimed at dealing with the failure analysis of reinforced concrete columns strengthened with carbon fiber reinforced plastic (CFRP) sheets including bond slip of the anchored reinforcing bars at the foot of the columns is presented. It is based on the yield design theory with a mixed modeling of the structure, according to which the concrete material is treated as a classical two dimensional continuum, whereas the longitudinal reinforcing bars are regarded as one dimensional rods including bond slip at the foot of the columns. In shear reinforced zones both the shear CFRP sheets and transverse reinforcing bars are incorporated in the analysis through a homogenization procedure and they are only in tension. The approach is then implemented numerically by means of the finite element formulation. The numerical procedure produces accurate estimates for the loading carrying capacity of the shear members taken as an illustrative application by correlation with the experimental results, so the proposed approach is valid.

Full-scale pullout tests of rock anchors in a limestone quarry focusing on bond failure at the anchor-grout and grout-rock interfaces

Rock anchors are a common safety measure for stabilising large-scale infrastructure,such as bridge towers,retaining walls,rock slopes and windmills.There are four principal failure modes for rock anchors:(a)tensile failure of the steel anchor,(b)anchor-grout interface failure,(c)grout-rock interface failure,and(d)rock mass uplift.Field tests were performed in a limestone quarry.These tests were designed to test failure modes B and C through pullout.In the tests of failure mode B,the shear stress on the anchor-grout interface is the largest at the top of the grout column and attenuates towards the distal end for small loads.The shear stress becomes uniformly distributed when the applied load is approximately 50%of the ultimate pullout load.The anchors designed to test failure mode C were installed with an endplate and had a higher toughness than the straight bar anchors.The shear stress on the grout-rock interface is the largest at the endplate and attenuates upward before slip starts along the interface.When the ultimate pullout load is reached,and the grout column starts to slip,the shear stress is approximately constant.The bond shear strength on the anchor-grout interface was approximately 20%of the uniaxial compressive strength of the grout,and the bond strength of the grout-rock interface was around 5%for that of the grout.The grout-rock interface is likely determined by whichever is weaker,the grout or the rock.

Impact of Dentinal Tubule Orientation on Dentin Bond Strength

This study aimed to determine the impact of dentinal tubule orientation on dentin bond strength to provide a reference for clinical cavity preparation in resin-bonded restoration. Patients aged 13-16 years were selected, including 18 males and 21 females. Forty-eight human maxillary first premolars from orthodontic extractions were chosen to prepare the test models with the dentinal tubule orientations perpendicular and parallel to the bonding substrate. The test models in the vertical and parallel groups were divided into three groups： total-etching with 20% phosphoric acid, total-etching with 35% phosphoric acid and self-etching, with the dentinal tubule surfaces bonded with composite resin blocks in each group. After the standard test models of dentinal tubule-composite resin blocks were placed in distilled water and stored at 37℃ for 24 h, shearing tests were performed using a universal material testing machine at a crosshead speed of 0.5 mm/min. The bond strength values in the vertical group were 19.33＋1.59 MPa for the 20% phosphoric acid group, 21.39±2.34 MPa for the 35% phosphoric acid group, and 16.88±1.54 MPa for the self-etching group. The bond strength values in the parallel group were 24.53±1.99 MPa for the 20% phosphoric acid group, 25.16＋2.88 MPa for the 35% phosphoric acid group, and 20.83±1.99 for the self-etching group. After using same total-etching adhesive, the shear bond strength of the parallel group was higher than that of the vertical group, and the difference was statistically significant （P〈0.05）. Regardless of vertical group or parallel group, the difference in the bond strength value between the total-etching groups and the self-etching group was statistically significant （P〈0.05）. It was concluded that the dentin bonding substrate which was parallel to the direction of the dentin tubule achieved an improved bond strength; the total-etching adhesives achieved higher bond strengths in dentin bond than the self-etching adhesives.

Rapid pressure-assisted sinter bonding in air using 200 nm Cu particles and enhancement of bonding strength by successive pressureless annealing

To design an effective and realistically applicable sinter bonding process for power devices,we proposed a two-step process using a 200 nm Cu-particle-based paste to form a bondline having high-temperature sustainability and superior thermal conductance.This process involved rapid pressure-assisted sinter bonding in air followed by pressureless annealing in a nitrogen atmosphere.In the case of a paste prepared with a mixture of 20 wt.%malic acid and 80 wt.%ethylene glycol,sinter bonding at 300℃and 5 MPa for only 30 s resulted in a sufficient shear strength of 23.1 MPa.The shear strength was significantly enhanced to 69.6 MPa by the additional pressureless aging for 30 min.Therefore,the two-step sinter bonding process is expected to provide an outstanding production rate as a next-generation sinter bonding process.

Bond Strength of Orthodontic Bracket Cement Using a Bleaching Light for Curing

Aim: To investigate the bond strengths achieved by using a Bleaching Curing Light (BCL) to polymerize orthodontic bonding cement. Material and Methods: 160 anterior bovine teeth were used to form 20 average sized human dental arches, and distributed into 2 groups according to which light curing method used: Group 1: BCL for 40 seconds, or Group 2: LED for 10 seconds. After storage in a controlled environment, Shear Bond Strength (SBS) and Adhesive Remnant Index (ARI) were determined. Results: Group 1 showed significantly lower SBS in the most posterior (first molar) position of the dental arch, (Group 1: 0.7 ± 1.0 MPa, Group 2: 2.9 ± 1.7 MPa, p Conclusion: Simultaneous full-arch curing of orthodontic bracket cement using a BCL is clinically acceptable in all but the most posterior locations along the dental arch.

不同清洁方法对高透氧化锆粘接强度和表面润湿性的影响

目的:研究不同清洁方法对唾液污染的高透氧化锆与自粘接树脂水门汀间剪切粘接强度和表面润湿性的影响。方法:制备80个高透氧化锆试件,随机分为5组(n=16),即对照组(无污染处理)、75%乙醇组、喷砂组、清洁剂组和大气压冷等离子体处理组等。测量表面接触角,测试剪切粘接强度,观察断裂模式。采用SPSS 26.0软件包对数据进行统计学分析。结果:大气压冷等离子体组的接触角最小(P<0.05);喷砂组、清洁剂组及大气压冷等离子体组的剪切粘接强度与对照组相比,无统计学差异(P>0.05),但均显著大于75%乙醇组(P<0.05);大气压冷等离子体组混合断裂模式增多。结论:喷砂、清洁剂及大气压冷等离子体清洁唾液污染的高透氧化锆,可获得与未被唾液污染前相当的粘接强度;大气压冷等离子体可显著提高高透氧化锆的表面润湿性。

胶粘剂粘度对CR/玻纤布复合胶布粘接性能的影响

针对氯丁橡胶和玻纤布的复合胶布,研究了胶粘剂粘度对复合胶布层间粘合强度和拉伸剪切强度的影响,并进行了分析。结果表明,随着胶粘剂粘度的逐渐降低,复合胶布的层间粘合强度和拉伸剪切强度先提高后降低,当胶粘剂流出时间为40~35 s时达到峰值。复合胶布的层间粘合试样破坏界面SEM显示,不同胶粘剂粘度试样的破坏界面呈现明显的差异。随着胶粘剂粘度的降低,6层复合胶布与金属轮之间的粘合强度同样呈现先提高后降低的现象,与复合胶布的层间粘合强度和拉伸剪切强度变化趋势一致。