Соболев В.В., Шиман Л.Н. Высокоэнергетическая обработка материалов. Сборник научных трудов

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Высокоэнергетическая обработка материалов

161

УДК 534.2

FRAGILE MATERIALS IN THE CONDITIONS

OF SUPERDEEP PENETRATION

J. Owsik

, S. Usherenko

, V. Malamud

, Y. Usherenko

, V. Sobolev

Institute of Optoelectronics Military University of Technology,

Kaliski Str., 2, Warsaw, Poland,

Ilan Ramon Youth Physics Center

in the Ben-Gurion University of the Negev,

SSI Institute of Technology of Metals of NAS of Belarus,

National Mining University of Ukraine, Dnepropetrovsk

JanOwsik@aster.pl,

usherenko@gmail.com,

malamudv@bgu.ac.il,

valeriysobolev@rambler.ru

Изучено поведение стеклянного и кремниевого монокристалла при воздействии сгустка

пылевых частиц. В условиях сверхглубокого проникновения защитные металлические по-

крытия становятся источником новых разрушительных факторов. Проникновение микро-

струй в объем стеклянного образца происходит в режиме прецессии относительно оси

движения потока. Форма следа поверхностных повреждений соответствует пилообразно-

му изменению параметров электромагнитной области

, которая управляет движением

плотных плазменных микроструй.

The behavior of glass and silicon monocrystal at impact of dust particles bunches is studied.

In the conditions of super deep penetration protective metal covers become a source of new

damaging factors. Penetration of microstreams into volume of the glass sample occurs in a mode

of a precession concerning an axis of stream movement into a barrier. The form of a strip of su-

perficial damages corresponds to sawtooth change of parameters of an electromagnetic field,

which controls movement of dense plasma microstreams.

Introduction

Damages of control systems during long flights essentially reduce reliability

and raise expenses of satellites and space stations using. Therefore, definition of

the reasons of these systems damage is the important problem. Streams of "galac-

tic" (high-energy) ions are admitted now as a principal cause of inexplicable and

not predicted failures of electronic control systems. The name "galactic" ions show

degree of this problem understanding. It is supposed, that in circumterraneous

space the rests of radiation streams from explosion of distant stars are moving in

not predicted directions. The increase in duration of flights in a space leads to in-

crease of probability of collision with a dust and elements of space dust [1]. If the

divergence with macroobjects (space dust) is carried out at the expense of maneu-

vering to find out bunches of a space dust, streams of "galactic" ions and to evade

from them is still unreal.

Usually collision of bunches of cosmic dust with metal aircraft modules are

Высокоэнергетическая обработка материалов

162

considered as the reason of erosion process of an external surface. However, the

English and American scientists have come to conclusion, that such collisions

cause appearance of plasma and damage of devices electronic control systems. It

has explained failures of exploratory modules in flights to Mars. The optimum

route of flight from the Earth to Mars passes through accumulations of dust clouds,

which considerably raises probability of collision of aircrafts with high-speed dust

bunches. Therefore the flight of the American exploratory module executed with

the greatest deviation from an optimum route [2], was successful.

Designing of a protective shell of a space vehicle is traditionally carried out

based on known barrier restriction at impact. Such restriction assumes, that the

relative depth of penetration of particles of space dust does not exceed six sizes of

a particle. It assumes that penetration depth of a high-speed particle in a protective

obstruction does not exceed several millimeters [3].

As the basic criterion of a striker penetration in the module the effect of loss

of tightness is traditionally used. At a collision with dust objects, a depressuriza-

tion is not observed. Feature of interacting over the range of super deep penetra-

tions (SDP) modes is origination a pulsing field of pressure in a protective obstruc-

tion and as the result of it, occurs a collapse of zones of a puncture. Therefore, at

the SDP loss of tightness of metal modules is absent [2].

In a mode of the SDP there is a barrier restriction in 10

-10

calibers of a

striker. Depth of particles penetration at the SDP modes (speed of particles accel-

eration 300-300 km/s) attains tens and hundreds millimeters. Depth of a penetra-

tion depends on a material of a protective obstruction and from parameters of a

dust bunch. Pressure level in zones of particles movement provides implementa-

tion of dynamic phase transition. A material from a solid phase passes into quasi-

liquid (dense plasma) condition. The pulsation of channel elements in a direction,

perpendicular to particle movement, leads to forming from a material of these

zones direct and return plasma streams (PS). Streams move in an obstruction and

then are thrown out (injected) from it. Intensive interacting of dust bunches and a

material of a protective obstruction in the closed volume leads to strong electric ef-

fects which at the expense of process dynamic initiate magnetic field oscillations.

Inside and round an obstruction originate strong electric and magnetic fields [3].

Now it is admitted existence of the fundamental problem originating at re-

search of super deep penetration effect. Estimations of a minimum quantity of the

energy necessary for super deep penetration, have shown, that the kinetic energy of

Высокоэнергетическая обработка материалов

163

a collision of a bunch of discrete strikers with an obstruction is less than 5-10 %

from total amount of energy expenses. In addition, it is experimentally established,

that super deep penetration of dust particles into metals is accompanied by numerous

power-intensive effects, for example, local fusion [3]. Thus, it is impossible to ex-

plain resistance decrease at striker movement in a solid body (in 100-10000 times)

by mechanisms of economical use of a kinetic energy from bunch impact at an ob-

struction. Explanation of this unusual phenomenon can be or the mechanism of ef-

fective transformation of an impact energy of a bunch in energy of movement of

separate strikers or a shock nuclear fusion with emission of additional energy [3].

Because of inertness of a heat transfer process it is impossible to remove an

excess of energy from the closed system in real time mode 10-8-10-3 sec. In high-

velocity processes, the energy excess at interaction particle-obstruction can be re-

moved by radiation. It is confirmed by that super deep penetration of dust particles

initiates radiation of streams of charged particles (ions). Energy of these particles at-

tains 80-250 MeV, that allows to classify them as "galactic" ions. Energy output in a

dynamic mode is realized at injection of microstreams of dense plasma from a pro-

tective obstruction and at interacting of plasma streams and an electromagnetic field.

The basic attention at research of super deep penetration of dust particles

concentrated on processes of their interaction with metal obstructions. Impact of

bunches of dust particles on a metal obstruction leads to appearance of micro-

streams from a material of a protective shell as the new damaging factor causing

fails of electronic control system of spacecrafts. In modern flying modules brittle

materials, for example, glass and a silicon monocrystal are also used.

The purpose of the given work is definition of results of deformation and

damage of these brittle materials in a mode of a super deep penetration.

1. Damages of glass samples in a mode of a super deep penetration

Obtaining of dust bunches and researches of their impact on brittle materials

have been carried out on the gun accelerator [4]. This technique allows to define

more precisely loading parameters (speed and time), than at use of explosive accel-

erators. In these experiments, the time of impact of a bunch on an obstruction was

≈35-50 microseconds. As substances of a bunch of discrete particles, a powder of

copper with density 5.5⋅10

kg/m

was used. A bunch with a length (20-36)⋅10

–3

and 10

–2

m diameter were accelerated till the speeds of 0.95-1.15 km/s [4]. The ob-

struction made of medium-carbon steel, contained the chamber for registration of

Высокоэнергетическая обработка материалов

164

penetrating particles. The chamber was sealed hermetically for exclusion of intro-

duction of extraneous dust particles.

Modeling of behavior of plates from Si monocrystal is convenient to carry out

based on studying of behavior of plates from glass. Glasses also are used as a mate-

rial for the protective modules. Glasses are called all amorphous bodies gained by

super-cooling of melt irrespective of their composition and temperature area of so-

lidification. Glasses possess mechanical properties of solids. Process of transition of

a liquid state in vitreous is reversible. In the field of low temperatures (lower t

–

glass transition temperature) glass along with diamond and quartz refers to the ideal

brittle material. Glass is capable to be destroyed under the influence of mechanical

efforts without an appreciable plastic deformation. As brittleness is most accurately

displayed at impact, it characterizes impact value - impact strength.

In reference glass at dynamic experiment, there are chips on a plate surface

(fig. 1). It was unexpected that despite glass brittleness through punctures of plates

(fig. 2) is registered. For plate research the light microscope in a mode of a direct

illumination of a surface (fig. 2а,) and in a mode of back illumination (fig. 2b,) was

used. The transversal size of an aperture after a puncture was (1-2)⋅10

-5

(fig. 2а,). The picture shown on fig. 2 c,d proves presence of through punching of

3 mm glass plate placed inside protective assemblage. The cross-section of a sur-

face of a puncture was in the form close to an ellipse.

Fig. 1. The surface of glass before and after dynamic experiment: a – refer-

ence glass, ×4000, – damage on glass, ×20000.

Высокоэнергетическая обработка материалов

165

Fig. 2. A surface of the glass sample after processing by microstreams at a di-

rect illumination a – ×1000, b – ×1000; at back illumination c – ×1000, d – ×1000

On a glass surface long-length superficial damages (fig. 3) are also detected.

The thickness of such defects is ≈10

-4

m (fig. 3а), and bandwidth of oscillations of

defects is approximately 4⋅10

-4

m (fig. 3b). Distance between phases of a curve of

damages oscillation is 9⋅10

-4

m. The form of the damages band corresponds to

sawtooth change of parameters of the electromagnetic field controlling movement

of a dense plasma microstream.

Fig. 3. Damages of a surface of the glass sample obtained in dynamic ex-

periment: a – ×400, b – ×400

a b

Высокоэнергетическая обработка материалов

166

Let us assume that for some reasons energy of a microstream is spent on a

surface of a glass plate. Then penetration of a stream inside of glass will be

blocked. However, on a fig. 2 we see through holes. Therefore, it is possible to as-

sert confidently, that microstreams penetrate on 3 mm into volume of a glass ob-

struction. The relation of a thickness of glass of 3⋅10

-3

m to diameter of an aperture

1⋅10

-5

-2⋅10

-5

m corresponds approximately to (1,5-3)⋅10

-2

calibers. We will in addi-

tion check such penetration. For this purpose, we use such property of glass, as a

transparency. Using of light microscope has allowed to establish, that observed on

fig. 3а tracks are on some depth under the surface [4]. The cycle of researches on

revealing of structure features of a damaged zone has been executed. Glasses have

been subjected to etching at different time by hydrofluoric acid solution. On fig. 4

change of structure of glass at various modes of etching is resulted.

Fig. 4. The structure of the SDP mode processed glass after various modes

of etching ×1000: a – 30 sec.; b – 60 sec.; c – 120 sec.

Along all thickness of a glass plate after dynamic processing tracks which

after etching are displayed as a zone with the changed physical and chemical prop-

erties [4] are observed. Therewith penetration of microstreams into glass volume

occurs in a mode of a precession concerning an axis of movement of a stream in an

obstruction, i.e. path of least effort. Pulsing character of striker interaction with a

glass obstruction after etching is observed on a fig. 3а. We see deviations of tracks

б а

Высокоэнергетическая обработка материалов

167

from an axis of stream introduction in the form of "M" in a lengthwise direction,

and in a form of corrugations in a cross-section (fig. 4b). The transverse pulsation

is appeared, as corrugations (ribs) on an external surface of a channel zone inside

glass. In a cross-section the etched (channel) zone reaches 3⋅10

-6

-6⋅10

-6

After 2

minute of the processed glass sample etching the defective material in a channel

zone is etched (fig. 4), radiation zone boundaries (the obscured walls of the chan-

nel) are displayed. In a cross-section the channel (etched) zone attains 1.1⋅10

-5

1.5⋅10

-5

m. Thus, as a result of consecutive etching of channel zones their diameter

varies at 11-15 times and the glass porous body is formed.

2. Damages of silicon monocrystal samples in the mode of super deep

penetration

As the base material of microchips applied to control systems in aviation and

space aircrafts, silicon monocrystals are used. In a complex the microchip can be

considered as a composite material, which zones have various mechanical and

physical properties [2]. From this position, we will consider penetration of micro-

streams into a plate of silicon monocrystal. So far as this material is not transparent

we will consider the transverse cleavages of Si plates (fig. 5).

In work [2] it was noted, that only few examples of through punching of the

single-crystal wafer by a dense plasma microstream are registered. Nevertheless it

is possible to observe examples of through and not through punching of a plate by

microstream without destruction (fig. 6). Punching of a fragile obstruction leads to

cleaving of a fragile plate. Using metal protective module has allowed to neutralize

dynamic impact of a high-speed particles bunch on plates.

Immediate cause of damage was powder particles, which acted only on the

protective steel module. Damage of plates occurred at the expense of an impact ac-

tion of plasma jets.

Presence of through punctures in a silicon plate proves that it is possible to

provide plastic deformation level, sufficient to compensate shock impact. It is pos-

sible to observe stably pictures of superficial damage of monocrystal silicon plates

without destruction (fig. 7).

From a figure 6 and 7 one can see, that the transverse size of a channel punc-

ture is 0.5-1 microns. Hence, the striker that has damaged the plate had analogous

transverse sizes. Such striker was generated as result of a complex of the physical

factors implemented at the super deep penetration. Process of the super deep

Высокоэнергетическая обработка материалов

168

Fig. 5. Zone of Si plate damage, ×200

Fig. 6. Puncture zones in plates from silicon monocrystal, ×300

penetration is realized in a protective shell of the steel module at impact of high-

speed bunch of discrete dust particles on it. At this condition in a narrow and

lengthy zone of a protective steel obstruction because of superposition of pressure

patterns the dynamic phase transition progresses, i.e. boundaries between phases

become apparent. Pressure level in these zones exceeds ≥10

N/m

[2]. Against

high local pressure intensive deformation processes (in a steel shell), leading to de-

structured substance condition are realized. These conditions correspond to the re-

a b

Высокоэнергетическая обработка материалов

169

quirements for condition of "super plasticity". The considerable part of the material

that has subjected to dynamic phase transition in the super deep penetration mode

(SDP) is injected in the form of direct and return streams of dense plasma at a col-

lapse of numerous channels [3].

Fig. 7. Zones of microstreams influence on a surface of a silicon monocrys-

tal: а – ×200, b – ×100

Hardness of silicon monocrystal is so high, that the scratching of this surface

can be made effectively only by diamond tool. Microhardness of silicon crystal ex-

ceeds 10

N/m

, hence, for creation of the surface defects shown on the fig. 7, higher

pressure of a striker on an obstruction and high speed (pressure level) is required.

3. The analysis of results of brittle materials punching

As process of the SDP proceeds in volume of steel obstruction in a time of

hundreds microseconds, restoration of reference low- defective conditions of mate-

rial by diffusion is not real. In work [5,6] it is shown, that in a steel obstruction

speed of substance stream movement (materials of an obstruction and an intro-

duced particle) in a direction of stream introduction is equal ν

=1482 m/s, and in

the transverse direction ν

com

=1048 m/s. In these conditions (P=11.3⋅10

N/m

) the

stream material passes in a condition of dense plasma [4].

At microdevice processing plasma jets pass in the experimental module

through gaps which exist between an internal surface of module protective wall and

an external surface of microcircuit shell, and also between an internal surface of a

microcircuit shell and silicon monocrystal surface. At width of gaps 1⋅10

-5

m, 3⋅10

-6

а б

Высокоэнергетическая обработка материалов

170

5⋅10

-6

m transit time of stream in them varies in the interval of time: 0.67⋅10

-6

sec-

onds, 2.02⋅10

-3.37⋅10

-6

seconds. Due to process of pressure unloading in microjet in

a contact zone between stream and monocrystal surface pressure varies over the

range: 11.32⋅10

N/m

, 1.17⋅10

-10

N/m

. As hardness of a silicon monocrystal is

not less, than 1⋅10

N/m

at decrease of stream pressure from 11.32⋅10

N/m

1⋅10

N/m

punching of crystal stops. In gaps pressure due to unloading (expansion)

of stream in the transverse direction decreases, and influence on silicon crystal

passes from a punching stage to a stage of local heating of crystal surface. [2].

Durability of a crystal at first approximation can be accepted equal to micro-

hardness, and compressibility of Si can be neglected. Then for an estimation of

punching depth and penetration speed of a stream it is possible to use Lavrentiev

equations [2]

, (1)

lL =

, (2)

where ρ

– density of stream material (iron), ρ

– density of obstruction material

(silicon), l – length of a stream.

For the variant of silicon plate puncture shown in work [2], U = 961 m/s,

l ≥ 98 microns. Microstreams penetrated into a silicon plate under an angle ≈60

(fig. 7). In a cleavage plane the depth of microstream penetration reaches 2⋅10

-4

According to the formula (2) length of the microstream used for Si plate damage is

l ≥10

microns. According to the formula (1) speed of this microstream is

U≥1300 m/s. The length of a stream in glass plate is l ≥1684 microns, and speed of

a stream into this material is U≥1290 m/s.

High speeds, pressure and lengths of microstreams formed in an obstruction

explain the main results of damage of materials and microcircuits observed at ex-

periments. For example, damage picture on monocrystal surface. Oscillatory char-

acter of surface damages (fig. 3, 7) explains by additional action of pulsing elec-

tromagnetic field on microstream from dense plasma.