A first intermediate roll of Sendzirmir mills was failure by surface spalling during operation. After analyzing by visual, stereo microscope, optical microscope, scanning electron microscope, glow-discharged spectrometer and hardness test, respectively, the results show that some voids and cracks existed on the contact surface as well as subsurface. Further examination verified inadequate hardn...

In this paper, we discuss two new paradigms for enabling costeffective III-V solar cell photovoltaics using (i) our novel layer transfer technology, called controlled spalling and (ii) new solar cell device structures. First, we present the application of the controlled spalling for making high-efficiency thin-film multijunction solar cells. Finally, a novel GaAs heterojunction solar cell struc...

This paper investigates the formation of the exit defects in carbon fibre-reinforced plates and characterizes their features in terms of drilling conditions. It was found that spalling and fuzzing are the major mechanisms of exit defects. The spalling, consisting of a main region and a secondary region, is caused by chisel and cutting edge actions, in which the former plays a key role. The fuzz...

Explosive spalling of pieces of concrete from the heated surface is considered to be the most dangerous effect of damage of concrete subjected to intense fire attack, especially when it occurs in restricted areas such as underground tunnels. Recent investigations have revealed that the amount of explosive spalling and the extent of cracking can considerably be reduced by use of suitable amount ...

Spalling of concrete in fire is due to dislodgement of small pieces of concrete. This phenomenon is one of the most detrimental effects causing damage or even failure of the concrete members during or after a fire by decreasing the residual mechanical properties and durability of the structure. In spite of many experimental and numerical studies, the real mechanism of spalling is still not well...

In this letter, we demonstrate the effectiveness of the controlled spalling technology for producing high-efficiency (28.7%) thin-film InGaP/(In)GaAs/Ge tandem solar cells. The controlled spalling technique was employed to separate the as-grown solar cell structure from the host Ge wafer followed by its transfer to an arbitrary Si support substrate. The structural and electrical properties of t...

I~VESTI~ATION OF MODES OF THERMAL FRACTURE OF SOME BRITTLE MATERIALS by CHARLES R. NELSON Submitted to the De~artment of Civil Engineering on September 2, 1969, in partial fulfillment of the requirements for the degree of Doctor of Philosophy. An analysis of the temperatures and the thermal stresses in a detailed and accurate manner with the finite element technique resulted in the following ad...

Accumulative roll bonding (ARB) was used to fabricate the Cu-Zn multilayer and Cu-Zn solid solution. A lamellar structure with the hardness of about 130 VHN was formed after eight ARB cycles. Following to the suitable heat treatment, a solid solution with a uniform microstructure and hardness of about 57 VHN was produced. The dominant wear mechanism in the ARB processed multilayer was found to ...

THE MECHANICAL behavior of brittle matrix composites is strongly affected by the bridging of cracks by fibers. In random fiber composites, libers can lie at an angle to the crack plane. Under such conditions, the bridging stress for a certain crack opening is governed by various micromcchanisms including fiber debonding, fiber bending and rupture as well as matrix spailing. While fiber debondin...

In the present paper a fully coupled three-dimensional thermo-hygro-mechanical model for concrete is discussed and used in the numerical studies. The model is formulated in the framework of continuum mechanics based on the principles of irreversible thermodynamics. Distribution of moisture, pore pressure, temperature, stresses and strains are calculated by employing a three-dimensional transien...