Zn-Based Alloys for Plain Bearings-Influence of Al and Cu Content on Mechanical Properties.

In recent decades, the requirements for plain bearing materials have continually increased, especially with new applications such as wind turbines, which require larger bearings. These new applications have completely different property profiles compared with, for example, bearings in automotive construction. Larger bearings need high strength and wear resistance, which established bearing materials cannot fulfill.

The effect of silicon microsegregation on the mechanical properties of high silicon alloyed ductile cast iron under monotonous loading.

High silicon alloyed ductile cast iron (Si-DCI) can show unpredictable brittle fracture which currently prevents a widespread application of this material. The brittleness is associated with local superstructure formation due to silicon segregation which influences the deformation mechanisms of the matrix phase. In order to understand the effect of silicon segregation on the mechanical properties of Si-DCI under monotonous loading, three alloys with different cooling conditions were examined and micromechanical simulations were carried out by using the phenomenological crystal plasticity model.

Numerical Modeling of Residual Stresses and Fracture Strengths of BaSrCoFeO in Reactive Air Brazed Joints.

Reactive Air Brazing (RAB) enables the joining of vacuum-sensitive oxide ceramics, such as BaSrCoFeO (BSCF), to metals in a one-step process. However, damage may form in ceramic or joint during RAB. In this work, experimental microstructure characterization, measurement, and prediction of local material properties using finite element analysis were combined to enlighten these damage mechanisms, which are currently not well understood.

Computation of the fracture probability and lifetime of all ceramic anterior crowns under cyclic loading - An FEA study.

Objectives: To predict the lifetime and fracture probability of anterior crowns made of a lithium disilicate glass-ceramic (IPS e.max CAD, LD, Ivoclar Vivadent, Liechtenstein) and a zirconia-containing lithium silicate glass-ceramic (Celtra Duo, ZLS, Dentsply Sirona, USA) under cycling loading.

Methods: Three-point bending tests were conducted to measure the viscoelastic parameters.

Influence of Different Build Orientations and Heat Treatments on the Creep Properties of Inconel 718 Produced by PBF-LB.

Inconel 718 is a nickel-based superalloy with excellent creep properties and good tensile and fatigue strength. In the field of additive manufacturing, it is a versatile and widely used alloy due to its good processability in the powder bed fusion with laser beam (PBF-LB) process. The microstructure and mechanical properties of the alloy produced by PBF-LB have already been studied in detail.

Influence of PBF-LB Process Atmosphere on the Fatigue Strength of Hot Isostatically Post-Densified Duplex Steel Parts Produced via the Shell Core Approach.

Laser-based additive manufacturing is a great manufacturing technology for producing parts of any geometry. To also increase the strength and reliability of parts produced via powder bed fusion with laser beam (PBF-LB), hot isostatic pressing (HIP) is often used to densify residual porosity or lack-of-fusion defects. When components are post-densified via HIP, they do not require a high density beforehand, only a closed porosity or a dense shell.

Novel Pectin Binder for Satelliting Carbides to H13 Tool Steel for PBF-LB Processing.

In order to enhance the range of processable alloys of laser-based powder bed fusion, reinforced alloys have gained focus. Satelliting is a recently introduced method for adding fine additives to larger parent powder particles using a bonding agent. Satellited particles prevent a local demixing due to size and density effects of the powder.

Diffusion Barriers Minimizing the Strength Degradation of Reactive Air Brazed BaSrCoFeO Membranes during Aging.

The separation of oxygen from air by means of inorganic ceramic membranes requires gas-tight ceramic-metal joints that enable reliable permeation operation in the oxygen partial pressure gradient at 850 °C. Reactive air brazing is a promising method to solve this challenge. However, reactive air brazed BSCF membranes suffer from a significant strength degradation that is caused by unhindered diffusion from the metal component during aging.

Failure Mechanisms of BaSrCoFeO Membranes after Pilot Module Operation.

The step from the testing of oxygen transport membranes on a lab scale to long-term operation on a large scale is a challenge. In a previous study, membrane failure was observed at defined positions of one end of the cooled tubular BaSrCoFeO membranes after an emergency shutdown. To understand the failure mechanisms, strength degradation and transient stress distribution were investigated by brittle-ring tests and finite element simulations, respectively.

Investigation on the Curvature and Stress Distribution of Laminates Based on an Analytic Solution and FE Simulation.

The potential combinations of favorable properties give metal-ceramic laminates (MCLs) a high degree of application flexibility. However, the different thermal expansion coefficients (CTEs) and shrinkage rates of the metals and ceramics during the co-sintering process often lead to large internal stresses that cause undesired deformation or even production failures. In practice, the identification of manufacturable MCLs relies on the "trial and error" principle, which usually requires a long development period.

Validation of the Powder Metallurgical Processing of Duplex Stainless Steels through Hot Isostatic Pressing with Integrated Heat Treatment.

Duplex stainless steels exhibit an excellent combination of corrosion resistance and strength and are increasingly being manufactured through powder metallurgy (PM) to produce large, near-net-shaped components, such as those used for offshore applications. Hot isostatic pressing (HIP) is often used for PM production, in which pre-alloyed powders are compacted under high pressures and temperatures. Recent developments in HIP technology enable fast cooling as part of the process cycle, reaching cooling rates comparable to oil quenching or even faster.

Potential of Metallurgical Gradients in the Design of Structural Components Made of Nodular Cast Iron.

The objective of this work is to investigate the use of metallurgical gradients (MG) in the design of structural components made of ductile cast iron (DCI). MG have been realized in this study by locally varying the pearlite fraction of the matrix. Exemplarily, the allowable cyclic load for a drive shaft as well as the allowable static displacement are calculated.

Strength characterization and lifetime prediction of dental ceramic materials.

Objective: To determine the Weibull modulus m, the characteristic strength σ,the subcritical crack growth (SCG) parameters (n &A) as well as the lifetime durability of three dental ceramic materials in water: a polycrystalline yttria-stabilized zirconia (Zenostar MT O, YSZ, Ivoclar Vivadent/Wieland, Germany), a lithium disilicate glass ceramic (IPS e.max CAD, LD, Ivoclar Vivadent, Liechtenstein), and a zirconia-containing lithium silicate glass ceramic (Celtra Duo, ZLS, Dentsply Sirona Inc, USA).

Methods: 30 specimens (Ø12 mm × 0.

Comparative Study of the Tempering Behavior of Different Martensitic Steels by Means of In-Situ Diffractometry and Dilatometry.

Martensitic steels are tempered to increase the toughness of the metastable martensite, which is brittle in the as-quenched state, and to achieve a more stable microstructure. During the tempering of steels, several particular overlapping effects can arise. Classical dilatometric investigations can only detect effects by monitoring the integral length change of the sample.

Field-Assisted Sintering/Spark Plasma Sintering of Gadolinium-Doped Ceria with Controlled Re-oxidation for Crack Prevention.

Gadolinium-Doped Ceria (GDC) is a prospective material for application in electrochemical devices. Free sintering in air of GDC powder usually requires temperatures in the range of 1400 to 1600 °C and dwell time of several hours. Recently, it was demonstrated that sintering temperature can be significantly decreased, when sintering was performed in reducing atmosphere.