Efficiency of High-Frequency Pressing of Spruce Laminated Timber Bonded with Casein Adhesives

This study identifies the importance of reducing press times by employing high-frequency pressing of spruce-laminated timber bound with sustainable casein adhesives. Spruce lamellas with dimensions of 12 × 10 × 75 cm were bonded into five-layered laminated timber and then separated into single-layer solid wood panels. Three types of casein (acid casein from two sources and rennin) were used. To compare the effectiveness of the casein formulation, two control samples bonded with polyvinyl acetate (PVAc) adhesive were pressed at room temperature (20 °C) and also with high-frequency equipment. The tests included compression shear strength, modulus of rupture, modulus of elasticity and screw withdrawal resistance on the wood panel surface and in the glue line. The average values of casein-bonded samples compression strengths ranged from 1.16 N/mm2 and 2.28 N/mm2, for modulus of rupture (MOR) were measured 85 N/mm2 to 101 N/mm2 and for modulus of elasticity (MOE) 12,200 N/mm2 to 14,300 N/mm2. The screw withdrawal resistance (SWR) on the surface of the wood panels ranged from 91 N/mm to 117 N/mm and in the adhesive line from 91 N/mm to 118 N/mm. Control samples bonded with PVAc adhesive did not perform better for compression shear strength, MOR and MOE, but for SWR in the adhesive line with 114 N/mm. Casein-bonded spruce timber pressed with HF equipment represents a sustainable new product with reduced press times, hazardous emissions and improved workability.

The Preparation of Aluminum-Bronze/Steel Duplex Metal by Loose Sintering

Aluminum-bronze/steel duplex metal has been prepared by aluminum-bronze powder whose compact oxide film was removed by dilute HCl solution before sintering. Scanning electronic microscope (SEM), energy spectrum analysis (EDS), density measurement and compression shear strength test were used to investigate the structure, composition, relative density and bond strength of aluminum-bronze/steel duplex metal. The results show: liquid phase could wet the aluminum-bronze powder washed by acid, improve sintering activity of the powder and increase bond strength of aluminum-bronze/steel interface. The relative density of sintered aluminum-bronze is 99.6%, and shear strength of aluminum-bronze/steel interface is 132.6MPa.

Study on Micstructure and Properties of Ceramic- Lined Composite Steel Pipes Produced by Centrifugal-SHS Process

The Al2O3 ceramic-lined steel pipes were made by SHS centrifugal process. The microstructure and phases in ceramic layer were investigated by SEM and X-ray diffraction, microstructure of the ceramic was observed with metallurgical microscope and compression-shear strength of the ceramic was tested by electronic universal testing machine, respectively. The results show that composite steel pipe is composed of three layers, including inner ceramic layer, transition iron layer and outer metal wall, compression-shear strength of the ceramic layer is up to 23 MPa. The percentage of porosity was tested by archimedes principle, it shows that porosity of ceramic was 5%; corrosion resistance of ceramic was tested by mass-loss method, corrosion resistance of ceramic coating is 0.95g/(h•m2).

The Bonding Properties of PVC Wood-Plastic Composite Materials Glued with Two Kinds of Adhesive

This paper aimed to confirm which adhesive is more suitable to glue the PVC wood-plastic composite materials between epoxy adhesive and J-39 acrylic ester adhesive. This paper tested compression shear strength and aging properties of PVC wood-plastic composite materials glued with these two adhesives. The results show that compression shear strength of PVC wood-plastic composite materials glued with epoxy adhesive is higher than with J-39 acrylic adhesives. Meanwhile, the setting time of two adhesives has effect on compression shearing strength. The results of aging properties after boiled and UV light treatment show that bonding properties of PVC wood-plastic composite materials glued with two adhesive were both degraded after aging，but bonding properties glued with epoxy adhesive was better than acrylic ester adhesive.

Compression and strength of dense sand at high pressures and elevated temperatures

The paper examines the stress–strain behaviour of densely compacted sand tested at pressures up to 80 MPa in one-dimensional compression and 7.2 MPa confining pressure in triaxial tests. Tests were performed at temperatures up to 100 °C. The testing relates to a proposal by Atomic Energy of Canada Limited to fill containers of waste nuclear fuel with a crushed quartz sand to provide additional stiffness. No significant effects of temperature were encountered in either isotropic compression or triaxial shear.Key words: sand, compression, shear strength, temperature, pressure.