Precision of surfaces machined on a lathe with geometric errors

The precision attained in the shape and mutual position of cylindrical surfaces after machining may be assessed by means of a mathematical model. The effectiveness of the model is confirmed in practice.     

Sound-absorbing polyurethane foam for the auto industry

Ambient noise harms the human organism: it produces high levels of the stress hormones, disrupts the operation of the nervous system, provokes cardiovascular damage, and impairs hearing. In the creation of new noise-reducing materials, the goal is to increase porosity without loss of structural strength. With greater porosity and reduced thickness, acoustic insulation will be lighter, which is better for use in automobiles. In addition, the dynamic characteristics are improved, and vehicle assembly is simplified.

     

Laser Machining of Tool Steels

Russian Engineering Research - Laser quenching and application of wear-resistant powder to the cutting edge of a hob is considered, with careful positioning of the laser spot. Experimental data are...     

Producing Polydicyclopentadiene from Lower-Grade Dicyclopentadiene

Russian Engineering Research - Polymer samples based on polydicyclopentadiene produced from Russian dicyclopentadiene are investigated by thermogravimetric analysis and differential scanning...     

Ball-End Mill with a Loxodromic Cutting Edge

Russian Engineering Research - Attention focuses on the design of a ball-end mill whose spherical section has a loxodromic cutting edge. The grinding width and depth required to obtain the rake and...     

Antimony segregation in stressed SiGe heterostructures grown by molecular beam epitaxy

The effects of the growth temperature, composition, and elastic strains in separate layers on the segregation of antimony are studied experimentally for stressed SiGe structures grown by molecular beam epitaxy. It is established that the growth conditions and parameters of the structures exert an interrelated influence on the segregation of Sb: the degree of the influence of the composition and elastic stresses in the SiGe layers on Sb segregation depends on the growth temperature. It is shown that usage of a method previously proposed by us for the selective doping of silicon structures with consideration for the obtained dependences of Sb segregation on the growth conditions and parameters of the SiGe layers makes it possible to form SiGe structures selectively doped with antimony.     

Annealing effect on reflectivity spectra of opal photonic crystals

We analyze broadband visible reflectivity spectra of opal photonic crystals annealed in an argon atmosphere and air. Scanning electron microscopic examination has shown that the crystals consist of close-packed spheres with a mean diameter in the range 200–290 nm. Incorporation of even small amounts of carbon (?0.5 wt %) increases the density of the opal matrix. The presence of carbon shifts the Bragg reflection peak of the opal and increases its intensity.     

Optical properties of three-dimensional magnetic opal photonic crystals

We have studied the optical properties of opal photonic crystals infiltrated with the M_0.35Zn_0.65Fe₂O₄ (M = Ni, Co) ferrites. The crystals consisted of amorphous SiO₂ nanospheres. The visible reflectivity spectra of the crystals were used to determine parameters of their photonic band gap and their refractive index.